Move apic cluster before pci_domain in MB Config.lb

[YhLu]

Accoding to Eric's idea to move cpu init before pci_device.

Move apic cluster before pci_domain in MB Config.lb

add some lines in northbridge.c

So in the MB Config.lb

apic cluster can only have one child.
Also can remove the northbridge/amd/k8  there is incoherent device under it.
For my 8 way system can keep MB Config.lb shorter.

Regards

Yinghai Lu