gpio/davinci: fix oops on unbanked gpio irq request

Unbanked GPIO irq setup code was overwriting chip_data leading
to the following oops on request_irq()

Unable to handle kernel paging request at virtual address febfffff
pgd = c22dc000
[febfffff] *pgd=00000000
Internal error: Oops: 801 [#1] PREEMPT
Modules linked in: mcu(+) edmak irqk cmemk
CPU: 0    Not tainted  (3.0.0-rc7+ #93)
PC is at irq_gc_mask_set_bit+0x68/0x7c
LR is at vprintk+0x22c/0x484
pc : [<c0080c0c>]    lr : [<c00457e0>]    psr: 60000093
sp : c33e3ba0  ip : c33e3af0  fp : c33e3bc4
r10: c04555bc  r9 : c33d4340  r8 : 60000013
r7 : 0000002d  r6 : c04555bc  r5 : fec67010  r4 : 00000000
r3 : c04734c8  r2 : fec00000  r1 : ffffffff  r0 : 00000026
Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 0005317f  Table: 822dc000  DAC: 00000015
Process modprobe (pid: 526, stack limit = 0xc33e2270)
Stack: (0xc33e3ba0 to 0xc33e4000)
3ba0: 00000000 c007d3d4 c33e3bcc c04555bc c04555bc c33d4340 c33e3bdc c33e3bc8
3bc0: c007f5f8 c0080bb4 00000000 c04555bc c33e3bf4 c33e3be0 c007f654 c007f5c0
3be0: 00000000 c04555bc c33e3c24 c33e3bf8 c007e6e8 c007f618 c01f2284 c0350af8
3c00: c0405214 bf016c98 00000001 00000000 c33dc008 0000002d c33e3c54 c33e3c28
3c20: c007e888 c007e408 00000001 c23ef880 c33dc000 00000000 c33dc080 c25caa00
3c40: c0487498 bf017078 c33e3c94 c33e3c58 bf016b44 c007e7d4 bf017078 c33dc008
3c60: c25caa08 c33dc008 c33e3c84 bf017484 c25caa00 c25caa00 c01f5f48 c25caa08
3c80: c0496d60 bf017484 c33e3ca4 c33e3c98 c022a698 bf01692c c33e3cd4 c33e3ca8
3ca0: c01f5d88 c022a688 00000000 bf017484 c25caa00 c25caa00 c01f5f48 c25caa08
3cc0: c0496d60 00000000 c33e3cec c33e3cd8 c01f5f8c c01f5d10 00000000 c33e3cf0
3ce0: c33e3d14 c33e3cf0 c01f5210 c01f5f58 c303cb48 c25ecf94 c25caa00 c25caa00
3d00: c25caa34 c33e3dd8 c33e3d34 c33e3d18 c01f6044 c01f51b8 c0496d3c c25caa00
3d20: c044e918 c33e3dd8 c33e3d44 c33e3d38 c01f4ff4 c01f5fcc c33e3d94 c33e3d48
3d40: c01f3d10 c01f4fd8 00000000 c044e918 00000000 00000000 c01f52c0 c034d570
3d60: c33e3d84 c33e3d70 c022bf84 c25caa00 00000000 c044e918 c33e3dd8 c25c2e00
3d80: c0496d60 bf01763c c33e3db4 c33e3d98 c022b1a0 c01f384c c25caa00 c33e3dd8
3da0: 00000000 c33e3dd8 c33e3dd4 c33e3db8 c022b27c c022b0e8 00000000 bf01763c
3dc0: c0451c80 c33e3dd8 c33e3e34 c33e3dd8 bf016f60 c022b210 5f75636d 746e6f63
3de0: 006c6f72 00000000 00000000 00000000 00000000 00000000 00000000 bf0174bc
3e00: 00000000 00989680 00000000 00000020 c0451c80 c0451c80 bf0174dc c01f5eb0
3e20: c33f0f00 bf0174dc c33e3e44 c33e3e38 c01f72f4 bf016e2c c33e3e74 c33e3e48
3e40: c01f5d88 c01f72e4 00000000 c0451c80 c0451cb4 bf0174dc c01f5eb0 c33f0f00
3e60: c0473100 00000000 c33e3e94 c33e3e78 c01f5f44 c01f5d10 00000000 c33e3e98
3e80: bf0174dc c01f5eb0 c33e3ebc c33e3e98 c01f5534 c01f5ec0 c303c038 c3061c30
3ea0: 00003cd8 00098258 bf0174dc c0462ac8 c33e3ecc c33e3ec0 c01f5bec c01f54dc
3ec0: c33e3efc c33e3ed0 c01f4d30 c01f5bdc bf0173a0 c33e2000 00003cd8 00098258
3ee0: bf0174dc c33e2000 c00301a4 bf019000 c33e3f1c c33e3f00 c01f6588 c01f4c8c
3f00: 00003cd8 00098258 00000000 c33e2000 c33e3f2c c33e3f20 c01f777c c01f6524
3f20: c33e3f3c c33e3f30 bf019014 c01f7740 c33e3f7c c33e3f40 c002f3ec bf019010
3f40: 00000000 00003cd8 00098258 bf017518 00000000 00003cd8 00098258 bf017518
3f60: 00000000 c00301a4 c33e2000 00000000 c33e3fa4 c33e3f80 c007b934 c002f3c4
3f80: c00b307c c00b2f48 00003cd8 00000000 00000003 00000080 00000000 c33e3fa8
3fa0: c0030020 c007b8b8 00003cd8 00000000 00098288 00003cd8 00098258 00098240
3fc0: 00003cd8 00000000 00000003 00000080 00098008 00098028 00098288 00000001
3fe0: be892998 be892988 00013d7c 40178740 60000010 00098288 09089041 00200845
Backtrace:
[<c0080ba4>] (irq_gc_mask_set_bit+0x0/0x7c) from [<c007f5f8>] (irq_enable+0x48/0x58)
 r6:c33d4340 r5:c04555bc r4:c04555bc
[<c007f5b0>] (irq_enable+0x0/0x58) from [<c007f654>] (irq_startup+0x4c/0x54)
 r5:c04555bc r4:00000000
[<c007f608>] (irq_startup+0x0/0x54) from [<c007e6e8>] (__setup_irq+0x2f0/0x3cc)
 r5:c04555bc r4:00000000
[<c007e3f8>] (__setup_irq+0x0/0x3cc) from [<c007e888>] (request_threaded_irq+0xc4/0x110)
 r8:0000002d r7:c33dc008 r6:00000000 r5:00000001 r4:bf016c98
[<c007e7c4>] (request_threaded_irq+0x0/0x110) from [<bf016b44>] (mcu_spi_probe+0x228/0x37c [mcu])
[<bf01691c>] (mcu_spi_probe+0x0/0x37c [mcu]) from [<c022a698>] (spi_drv_probe+0x20/0x24)
[<c022a678>] (spi_drv_probe+0x0/0x24) from [<c01f5d88>] (driver_probe_device+0x88/0x1b0)
[<c01f5d00>] (driver_probe_device+0x0/0x1b0) from [<c01f5f8c>] (__device_attach+0x44/0x48)
[<c01f5f48>] (__device_attach+0x0/0x48) from [<c01f5210>] (bus_for_each_drv+0x68/0x94)
 r5:c33e3cf0 r4:00000000
[<c01f51a8>] (bus_for_each_drv+0x0/0x94) from [<c01f6044>] (device_attach+0x88/0xa0)
 r7:c33e3dd8 r6:c25caa34 r5:c25caa00 r4:c25caa00
[<c01f5fbc>] (device_attach+0x0/0xa0) from [<c01f4ff4>] (bus_probe_device+0x2c/0x4c)
 r7:c33e3dd8 r6:c044e918 r5:c25caa00 r4:c0496d3c
[<c01f4fc8>] (bus_probe_device+0x0/0x4c) from [<c01f3d10>] (device_add+0x4d4/0x648)
[<c01f383c>] (device_add+0x0/0x648) from [<c022b1a0>] (spi_add_device+0xc8/0x128)
[<c022b0d8>] (spi_add_device+0x0/0x128) from [<c022b27c>] (spi_new_device+0x7c/0xb4)
 r7:c33e3dd8 r6:00000000 r5:c33e3dd8 r4:c25caa00
[<c022b200>] (spi_new_device+0x0/0xb4) from [<bf016f60>] (mcu_probe+0x144/0x224 [mcu])
 r7:c33e3dd8 r6:c0451c80 r5:bf01763c r4:00000000
[<bf016e1c>] (mcu_probe+0x0/0x224 [mcu]) from [<c01f72f4>] (platform_drv_probe+0x20/0x24)
[<c01f72d4>] (platform_drv_probe+0x0/0x24) from [<c01f5d88>] (driver_probe_device+0x88/0x1b0)
[<c01f5d00>] (driver_probe_device+0x0/0x1b0) from [<c01f5f44>] (__driver_attach+0x94/0x98)
[<c01f5eb0>] (__driver_attach+0x0/0x98) from [<c01f5534>] (bus_for_each_dev+0x68/0x94)
 r7:c01f5eb0 r6:bf0174dc r5:c33e3e98 r4:00000000
[<c01f54cc>] (bus_for_each_dev+0x0/0x94) from [<c01f5bec>] (driver_attach+0x20/0x28)
 r7:c0462ac8 r6:bf0174dc r5:00098258 r4:00003cd8
[<c01f5bcc>] (driver_attach+0x0/0x28) from [<c01f4d30>] (bus_add_driver+0xb4/0x258)
[<c01f4c7c>] (bus_add_driver+0x0/0x258) from [<c01f6588>] (driver_register+0x74/0x158)
[<c01f6514>] (driver_register+0x0/0x158) from [<c01f777c>] (platform_driver_register+0x4c/0x60)
 r7:c33e2000 r6:00000000 r5:00098258 r4:00003cd8
[<c01f7730>] (platform_driver_register+0x0/0x60) from [<bf019014>] (mcu_init+0x14/0x20 [mcu])
[<bf019000>] (mcu_init+0x0/0x20 [mcu]) from [<c002f3ec>] (do_one_initcall+0x38/0x170)
[<c002f3b4>] (do_one_initcall+0x0/0x170) from [<c007b934>] (sys_init_module+0x8c/0x1a4)
[<c007b8a8>] (sys_init_module+0x0/0x1a4) from [<c0030020>] (ret_fast_syscall+0x0/0x2c)
 r7:00000080 r6:00000003 r5:00000000 r4:00003cd8
Code: e1844003 e585400c e596300c e5932064 (e7814002)

Fix the issue.

Cc: <stable@vger.kernel.org> # v3.0.x+
Reported-by: Jon Povey <Jon.Povey@racelogic.co.uk>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>