powerpc: is_hugepage_only_range() must account for both 4kB and 64kB slices

commit 9ba0fdbfaed2e74005d87fab948c5522b86ff733 upstream.

powerpc: is_hugepage_only_range() must account for both 4kB and 64kB slices

The subpage_prot syscall fails on second and subsequent calls for a given
region, because is_hugepage_only_range() is mis-identifying the 4 kB
slices when the process has a 64 kB page size.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>