can: fix memory leak in initial namespace support

The can_rx_alldev_list is a per-net data structure now and allocated in
can_pernet_init(). Make sure the memory is free'd in can_pernet_exit() too.

Signed-off-by: Oliver Hartkopp <[e-mail]>
Signed-off-by: Marc Kleine-Budde <[e-mail]>

net/can/af_can.c

···
 		}
 	}
 	rcu_read_unlock();
+
+	kfree(net->can.can_rx_alldev_list);
 }
 
 /*