the interface conversion to platform.pci_intr_route(). I've left the
platform.pci_intr_route() function pointer in place, as well as
alpha_pci_route_interrupt(), but no platform currently implements it.
To work around the removal of alpha_platform_assign_pciintr(cfg);
from the pci probe code, I've hooked in calls to platform.pci_intr_map()
in pcib_read_config (similar to the x86 APIC_IO ifdef in pci_cfgregread)
for every chipset that has a platform which needs it.
While here, I've removed the interupt mapping/routing code from the
AS2x00 platform because its not required (it has never been present in
-stable).
Tested on: UP1000, Miata(GL), XP1000, AS2100, AS500
150cd07213