powerpc/vphn: move VPHN parsing logic to a separate file

The goal behind this patch is to be able to write userland tests for the
VPHN parsing code.

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --cc arch/powerpc/mm/Makefile
Simple merge

diff --cc arch/powerpc/mm/numa.c
Simple merge

diff --cc arch/powerpc/mm/vphn.c
Simple merge

diff --cc arch/powerpc/mm/vphn.h
Simple merge