futex: Convert to use the preferred 'fallthrough' macro

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200813122117.51173-1-linmiaohe@huawei.com

Author: MiaoheLin

kernel/futex.c

@@ -3744,12 +3744,12 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 	switch (cmd) {
 	case FUTEX_WAIT:
 		val3 = FUTEX_BITSET_MATCH_ANY;
-		/* fall through */
+		fallthrough;
 	case FUTEX_WAIT_BITSET:
 		return futex_wait(uaddr, flags, val, timeout, val3);
 	case FUTEX_WAKE:
 		val3 = FUTEX_BITSET_MATCH_ANY;
-		/* fall through */
+		fallthrough;
 	case FUTEX_WAKE_BITSET:
 		return futex_wake(uaddr, flags, val, val3);
 	case FUTEX_REQUEUE: