[POWERPC] Add basic PCI/PCI Express support for 8544DS board

Add basic support for the PCIe PHB and enable the ULI bridge.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>