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 <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
diff --git a/net/can/af_can.c b/net/can/af_can.c
index abf7d85..2c935ba 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -903,6 +903,8 @@ static void can_pernet_exit(struct net *net)
 		}
 	}
 	rcu_read_unlock();
+
+	kfree(net->can.can_rx_alldev_list);
 }
 
 /*