Log Message:
   Replace the hooribly overloaded use of pci_enumerate_bus() - to find out
   the chipset revision - by pci_find_device().
   While the latter isn't better technically (works around the otherwise
   hierarchical device tree), using it doesn't require PCI configuration
   functions to support stuff which philosophically doesn't belong there.
   So we get the hands free to restructure things for better loadable
   driver support.
   (Actually, since this is about chipset internal IDE interfaces where
   the PCI device/function numbers are well known, this all is unnecessary.)


pci_find_device() fails in the case of >1 matching device.  is this
going to be a problem for this change?  (i'm not familiar with what
viaide is but i'd expect it to be onboard ide...?)