mm: adjust apply_to_pfn_range interface for dropped token.

mm/pgtable: drop pgtable_t variable from pte_fn_t functions
drops the token came in via the hmm tree, this caused lots of
conflicts, but applying this cleanup patch should reduce it
to something easier to handle. Just accept the token is unused
at this point.

Signed-off-by: Dave Airlie <airlied@redhat.com>