[PATCH] powerpc: pci_64 fixes & cleanups

I discovered that in some cases (PowerMac for example) we wouldn't
properly map the PCI IO space on recent kernels. In addition, the code
for initializing PCI host bridges was scattered all over the place with
some duplication between platforms.

This patch fixes the problem and does a small cleanup by creating a
pcibios_alloc_controller() in pci_64.c that is similar to the one in
pci_32.c (just takes an additional device node argument) that takes care
of all the grunt allocation and initialisation work. It should work for
both boot time and dynamically allocated PHBs.

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