PCI: separate pci_setup_bridge to small functions

This is a good cleanup in itself, and makes it easier to modify specific
resource types in later code.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>