powerpc/p1023: set IRQ[4:6,11] to active-high level sensitive for PCIe

P1023 external IRQ[4:6, 11] are not pin out, but the interrupts are
utilized by the PCIe controllers.  As they are not exposed as pins we
need to set them as active-high (internal to the SoC these interrupts
are pulled down).

IRQs[0:3,7:10] are pulled up on the board so we have them set as
active-low.

Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>