thp: mprotect: pass vma down to page table walkers

Flushing the tlb for huge pmds requires the vma's anon_vma, so pass along
the vma instead of the mm, we can always get the latter when we need it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>