[PARISC] Fix PCI bus numbering in the presence of Cardbus bridges

Firmware ignores Cardbus bridges, so when Linux assigns bus numbers,
it must override firmware's notion of what the busses are numbered.
This is not sufficient to support the Cardbus bridge as there is also
no interrupt routing table entry for them.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>