[POWERPC] Merge PCI resource fixups

The PCI code in 32 and 64 bits fixes up resources differently.

32 bits uses a header quirk plus handles bridges in pcibios_fixup_bus()
while 64 bits does things in various places depending on whether you
are using OF probing, using PCI hotplug, etc...

This merges those by basically using the 32 bits approach for both,
with various tweaks to make 64 bits work with the new approach.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>