dev: always advertise the new nsid when the netns iface changes

The user should be able to follow any interface that moves to another
netns.  There is no reason to hide physical interfaces.

CC: Jiri Benc <jbenc@redhat.com>
CC: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Jiri Benc <jbenc@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: NicolasDichtel

net/core/dev.c

@@ -8529,10 +8529,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
 	call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
 	rcu_barrier();
 	call_netdevice_notifiers(NETDEV_UNREGISTER_FINAL, dev);
-	if (dev->rtnl_link_ops && dev->rtnl_link_ops->get_link_net)
-		new_nsid = peernet2id_alloc(dev_net(dev), net);
-	else
-		new_nsid = peernet2id(dev_net(dev), net);
+	new_nsid = peernet2id_alloc(dev_net(dev), net);
 	rtmsg_ifinfo_newnet(RTM_DELLINK, dev, ~0U, GFP_KERNEL, &new_nsid);
 
 	/*