PCI_BUS_FIXUP for amd64

I recently updated my amd64 laptop to -current, and lost my pccbb device.

Looking at PCI_BUS_FIXUP, I see that the option is honored, but nothing 
seems to be done on this port.  So I moved the pci fixup code in 
arch/i386 to arch/x86 and enabled it for amd64 as well.  It fixes my 
problem, and I believe that it is relatively common that pccbb's (card 
bus bridges) are left unintialized by the BIOS.
Is it acceptable (and a good idea) to commit this change?

skd