If an error occurs when the netdevice is moved to the link netns, a full cleanup
must be done.

Fixes: 317f4810 ("rtnl: allow to create device with IFLA_LINK_NETNSID set")
Signed-off-by: NNicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>