[NETNS]: DST cleanup routines should be called inside namespace.

Device inside the namespace can be started and downed. So, active routing
cache should be cleaned up on device stop.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dst.c

@@ -295,9 +295,6 @@ static int dst_dev_event(struct notifier_block *this, unsigned long event, void
 	struct net_device *dev = ptr;
 	struct dst_entry *dst, *last = NULL;
 
-	if (dev->nd_net != &init_net)
-		return NOTIFY_DONE;
-
 	switch (event) {
 	case NETDEV_UNREGISTER:
 	case NETDEV_DOWN: