veth: Fix unregister_netdevice_queue for veth

I tested the recent unregister many changes and got a weird,
nasty and seemingly unrelasted kernel oops. Changing
unregister_netdevice_queue to use list_move_tail fixes
the problem for me.

ip link add type veth
rmmod veth

ls /sys/class/net/
showed one of the veth devices still present.

A subsequent ip link oopsed the box.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>