The tile support for multiple-size huge pages requires tagging
the hugetlb PTE with a "super" bit for PTEs that are multiples of
the basic size of a pagetable span.  To set that bit properly
we need to tweak the PTe in make_huge_pte() based on the vma.

This change provides the API for a subsequent tile-specific
change to use.
Reviewed-by: NHillf Danton <dhillf@gmail.com>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>