powerpc/44x: Add support PCI-E for APM821xx SoC and Bluestone board

This patch extends PCI-E driver to support PCI-E for APM821xx SoC on Bluestone
board.

Signed-off-by: Vinh Nguyen Huu Tuong <vhtnguyen@apm.com>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>