powerpc/powernv: I/O and MMIO resource assignment for PEs

powerpc/powernv: I/O and MMIO resource assignment for PEs

There're 2 types of PCI bus sensitive PEs: (A) The PE includes
single PCI bus. (B) The PE includes the PCI bus and all the subordinate
PCI buses, and the patch tries to assign I/O and MMIO resources
based on created PEs. Fortunately, we figured out unified scheme
to do resource assignment for all types of PCI bus based PEs according
to Ben's idea:

        - Resource assignment based on PE from top to bottom.
        - The soureces, either I/O or MMIO, of the PE are figured out
          from the assigned PCI bus.
        - The occupied resource by parent PE could possibilly be overrided
          by children PEs.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Reviewed-by: Richard Yang <weiyang@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>