x86/pci: seperate x86_pci_rootbus_res_quirks from amd_bus.c

Those functions are used by intel_bus.c so seperate them to another file. and
make amd_bus a bit smaller.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>