mlxsw: fix SWITCHDEV_OBJ_ID_PORT_MDB

There is a missing break statement so we always return -EOPNOTSUPP.

Fixes: 3a49b4fde2 ('mlxsw: Adding layer 2 multicast support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c

@@ -1015,6 +1015,7 @@ static int mlxsw_sp_port_obj_del(struct net_device *dev,
 	case SWITCHDEV_OBJ_ID_PORT_MDB:
 		err = mlxsw_sp_port_mdb_del(mlxsw_sp_port,
 					    SWITCHDEV_OBJ_PORT_MDB(obj));
+		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;