powerpc/powernv: PE list based on creation order

The resource (I/O and MMIO) will be assigned on basis of PE from
top to bottom so that we can implement the trick here: the resource
that has been assigned to parent PE could be taken by child PE if
necessary.

The current implementation already has PE list per PHB basis, but
the list doesn't meet our requirment: tracing PE based on their
cration time from top to bottom. So the patch does rename for the
DMA based PE list and introduces the list to trace the PEs sequentially
based on their creation time.

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>