aufs: bugfix, possible kmemleak

In aufs5.4, kmemleak reported several false positives in
fs/aufs/xino.c.  I don't know why, but it may be related to the
"delayed" kfree (by RCU).  So I simply replace it by direct kfree()
call.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 03836b8128073f92b4e4a1cb54f91d0d7c290d1f)

fs/aufs/xino.c

@@ -1344,7 +1344,8 @@ static void au_xino_release(struct kref *kref)
 		hlist_bl_lock(hbl);
 		hlist_bl_for_each_entry_safe(p, pos, n, hbl, node) {
 			hlist_bl_del(&p->node);
-			au_kfree_rcu(p);
+			/* kmemleak reported au_kfree_rcu() doesn't free it */
+			kfree(p);
 		}
 		hlist_bl_unlock(hbl);
 	}