NFC: Fix sleeping in atomic when releasing socket

nfc_llcp_socket_release is calling lock_sock/release_sock while holding
write lock for rwlock. Use bh_lock/unlock_sock instead.

BUG: sleeping function called from invalid context at net/core/sock.c:2138
in_atomic(): 1, irqs_disabled(): 0, pid: 56, name: kworker/1:1
4 locks held by kworker/1:1/56:
Pid: 56, comm: kworker/1:1 Not tainted 3.5.0-999-nfc+ #7
Call Trace:
[<ffffffff810952c5>] __might_sleep+0x145/0x200
[<ffffffff815d7686>] lock_sock_nested+0x36/0xa0
[<ffffffff81731569>] ? _raw_write_lock+0x49/0x50
[<ffffffffa04aa100>] ? nfc_llcp_socket_release+0x30/0x200 [nfc]
[<ffffffffa04aa122>] nfc_llcp_socket_release+0x52/0x200 [nfc]
[<ffffffffa04ab9f0>] nfc_llcp_mac_is_down+0x20/0x30 [nfc]
[<ffffffffa04a6fea>] nfc_dep_link_down+0xaa/0xf0 [nfc]
[<ffffffffa04a9bb5>] nfc_llcp_timeout_work+0x15/0x20 [nfc]
[<ffffffff810825f7>] process_one_work+0x197/0x7c0
[<ffffffff81082596>] ? process_one_work+0x136/0x7c0
[<ffffffff8172fbc9>] ? __schedule+0x419/0x9c0
[<ffffffffa04a9ba0>] ? nfc_llcp_build_gb+0x1b0/0x1b0 [nfc]
[<ffffffff81083090>] worker_thread+0x190/0x4c0
[<ffffffff81082f00>] ? rescuer_thread+0x2a0/0x2a0
[<ffffffff81088d1e>] kthread+0xae/0xc0
[<ffffffff810caafd>] ? trace_hardirqs_on+0xd/0x10
[<ffffffff8173acc4>] kernel_thread_helper+0x4/0x10
[<ffffffff81732174>] ? retint_restore_args+0x13/0x13
[<ffffffff81088c70>] ? flush_kthread_worker+0x150/0x150
[<ffffffff8173acc0>] ? gs_change+0x13/0x13

Signed-off-by: Szymon Janc <szymon.janc@tieto.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>