staging: rtlwifi: mark expected switch fall-through in rtl_make_smps_action

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtlwifi/base.c

@@ -2335,9 +2335,7 @@ static struct sk_buff *rtl_make_smps_action(struct ieee80211_hw *hw,
 	case IEEE80211_SMPS_AUTOMATIC:/* 0 */
 	case IEEE80211_SMPS_NUM_MODES:/* 4 */
 		WARN_ON(1);
-	/* Here will get a 'MISSING_BREAK' in Coverity Test, just ignore it.
-	 * According to Kernel Code, here is right.
-	 */
+	/* fall through */
 	case IEEE80211_SMPS_OFF:/* 1 */ /*MIMO_PS_NOLIMIT*/
 		action_frame->u.action.u.ht_smps.smps_control =
 				WLAN_HT_SMPS_CONTROL_DISABLED;/* 0 */