Currently, some PCIe devices on POWER6 machines do not get interrupts
assigned correctly.  The problem is that OF doesn't create an
"interrupt" property for them.  The fix is for of_irq_map_pci to fall
back to using the value in the PCI interrupt-pin register in config
space, as we do when there is no OF device-tree node for the device.

I have verified that this works fine with a pair of Squib-E SAS
adapter on a P6-570.
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>