powerpc/pci: Override pcibios_setup_bridge()

This overrides pcibios_setup_bridge() that is called to update PCI
bridge windows when PCI resource assignment is completed, to assign
PE and setup various (resource) mapping for the PE in subsequent
patches.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>