[POWERPC] pci32: Remove PowerMac P2P bridge IO hack

The 32 bits PowerPC PCI code has a hack for use by some PowerMacs
to try to re-open PCI<->PCI bridge IO resources that were closed
by the firmware.  This is no longer necessary as the generic code
will now do that for us.

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