net/mlx5: E-Switch, Fail mlx5_esw_modify_vport_rate if qos disabled

Avoid calling mlx5_esw_modify_vport_rate() if qos is not enabled and
avoid unnecessary syndrome messages from firmware.

Fixes: fcb64c0f ("net/mlx5: E-Switch, add ingress rate support")
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/eswitch.c

@@ -1142,6 +1142,10 @@ int mlx5_esw_modify_vport_rate(struct mlx5_eswitch *esw, u16 vport_num,
 	struct mlx5_vport *vport;
 
 	vport = mlx5_eswitch_get_vport(esw, vport_num);
+
+	if (!vport->qos.enabled)
+		return -EOPNOTSUPP;
+
 	MLX5_SET(scheduling_context, ctx, max_average_bw, rate_mbps);
 
 	return mlx5_modify_scheduling_element_cmd(esw->dev,