powerpc/pci: Properly allocate bus resources for hotplug PHBs

Resources for PHB's that are dynamically added to a system are not
properly allocated in the resource tree.

Not having these resources allocated causes an oops when removing
the PHB when we try to release them.

The diff appears a bit messy, this is mainly due to moving everything
one tab to the left in the pcibios_allocate_bus_resources routine.
The functionality change in this routine is only that the
list_for_each_entry() loop is pulled out and moved to the necessary
calling routine.

Signed-off-by: Nathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>