powerpc/85xx: Fix PCIe IDSEL for Px020RDB

PCIe device in legacy mode can trigger interrupts using the wires #INTA,
#INTB ,#INTC and #INTD. PCI devices are obligated to use #INTx for
interrupts under legacy mode.  Each PCI slot or device is typically wired
to different inputs on the interrupt controller.

So, Define interrupt-map and interrupt-map-mask properties for device tree
to of map each PCI interrupt signal to the inputs of the interrupt
controller.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>