mm: rename drop_anon_vma() to put_anon_vma()

The normal code pattern used in the kernel is: get/put.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/migrate.c

@@ -764,7 +764,7 @@ skip_unmap:
 
 	/* Drop an anon_vma reference if we took one */
 	if (anon_vma)
-		drop_anon_vma(anon_vma);
+		put_anon_vma(anon_vma);
 
 uncharge:
 	if (!charge)
@@ -856,7 +856,7 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 		remove_migration_ptes(hpage, hpage);
 
 	if (anon_vma)
-		drop_anon_vma(anon_vma);
+		put_anon_vma(anon_vma);
 out:
 	unlock_page(hpage);