rocker: fix rocker_world_port_obj_vlan_add()

We were changing return values and accidentally made
rocker_world_port_obj_vlan_add() into a no-op.

Fixes: fccd84d4 ('rocker: return -EOPNOTSUPP for undefined world ops')
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/rocker/rocker_main.c

@@ -1598,7 +1598,6 @@ rocker_world_port_obj_vlan_add(struct rocker_port *rocker_port,
 
 	if (!wops->port_obj_vlan_add)
 		return -EOPNOTSUPP;
-		return 0;
 	return wops->port_obj_vlan_add(rocker_port, vlan, trans);
 }