block/commit: Drop bdrv_child_try_set_perm()

commit_top_bs never requests or unshares any permissions.  There is no
reason to make this so explicit here.
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/commit.c

@@ -110,8 +110,6 @@ static void commit_abort(Job *job)
      * XXX Can (or should) we somehow keep 'consistent read' blocked even
      * after the failed/cancelled commit job is gone? If we already wrote
      * something to base, the intermediate images aren't valid any more. */
-    bdrv_child_try_set_perm(s->commit_top_bs->backing, 0, BLK_PERM_ALL,
-                            &error_abort);
     bdrv_replace_node(s->commit_top_bs, backing_bs(s->commit_top_bs),
                       &error_abort);