linux-phytec-ti

powerpc/mm: Handle _PTE_NONE_MASK

I am splitting this as a separate patch to get better review. If ok
we should merge this with previous patch.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>