Bluetooth: RFCOMM: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1].

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/rfcomm/core.c

@@ -479,7 +479,7 @@ static int __rfcomm_dlc_close(struct rfcomm_dlc *d, int err)
 		/* if closing a dlc in a session that hasn't been started,
 		 * just close and unlink the dlc
 		 */
-		/* fall through */
+		fallthrough;
 
 	default:
 		rfcomm_dlc_clear_timer(d);

net/bluetooth/rfcomm/sock.c

@@ -218,7 +218,7 @@ static void __rfcomm_sock_close(struct sock *sk)
 	case BT_CONFIG:
 	case BT_CONNECTED:
 		rfcomm_dlc_close(d, 0);
-		/* fall through */
+		fallthrough;
 
 	default:
 		sock_set_flag(sk, SOCK_ZAPPED);