We usually destroy the netdev's router interface (RIF) when the last IP
address is removed from it.

However, we shouldn't do that if it's enslaved to an L3 master device.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>