can: j1939: fix memory leak if filters was set

Filters array is coped from user space and linked to the j1939 socket.
On socket release this memory was not freed.

Fixes: 9d71dd0c ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

net/can/j1939/socket.c

@@ -580,6 +580,7 @@ static int j1939_sk_release(struct socket *sock)
 		j1939_netdev_stop(priv);
 	}
 
+	kfree(jsk->filters);
 	sock_orphan(sk);
 	sock->sk = NULL;