[ Upstream commit aabb9875 ]

The missing call to unregister_netdev() leaves the interface active
after the driver is unloaded by rmmod.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>