powerpc/PCI: move fixup hooks from __init to __devinit

powerpc/PCI: move fixup hooks from __init to __devinit

The fixups are executed once the pci-device is found which is during
boot process so __init seems fine as long as the platform does not
support hotplug.

However it is possible to remove the PCI bus at run time and have it
rediscovered again via "echo 1 > /sys/bus/pci/rescan" and this will call
the fixups again.

Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>