[POWERPC] Use for_each_ matching routinues for pci PHBs

On the Freescale embedded (83xx, 85xx, 86xx) and a few of the discrete
bridges (mpc10x, tsi108) use the new for_each_compatible_node() or
for_each_node_by_type() to provide more exact matching when looking for
PHBs in the device tree.

With the previous code it was possible to match on pci bridges since
we were only matching on device_type.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>