mlxsw: spectrum_router: Veto unsupported RIF MAC addresses

On NETDEV_PRE_CHANGEADDR, if the change is related to a RIF interface,
verify that it satisfies the criterion that all RIF interfaces have the
same MAC address prefix, as indicated by mlxsw_sp.mac_mask.

Additionally, besides explicit address changes, check that the address
of an interface for which a RIF is about to be added matches the
required pattern as well.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>