Bluetooth: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/rfcomm/sock.c

@@ -221,6 +221,7 @@ static void __rfcomm_sock_close(struct sock *sk)
 	case BT_CONFIG:
 	case BT_CONNECTED:
 		rfcomm_dlc_close(d, 0);
+		/* fall through */
 
 	default:
 		sock_set_flag(sk, SOCK_ZAPPED);