scan AMD opteron io/mmio routing to make sure every pci root bus get correct
resource range. Thus later pci scan could assign correct resource to device
with unassigned resource.

this can fix a system without _CRS for multi pci root bus.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>