First cut at getting the ISA routing working. If we can't route a PCI
interrupt for the CSC interrupt, then we revert to ISA. If we didn't
have an interrupt set up with hw.pcic.irq, then do polling.

Also, don't complain about ignoring function 1 for any devices except
pcic devices. This would normally only show up if someone set
hw.pcic.ignore_function_1=1.

MFC: as soon as I can test it on some troublesome laptops.