powerpc/44x: Adding PCI-E support for PowerPC 460SX based SOC.

Add support for PCI-e on the AMCC 460SX boards

Signed-off-by: Tirumala Marri <tmarri@amcc.com>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>