net/mlx5: Disallow RoCE on multi port slave device

In dual port mode, setting roce enabled/disable for the slave device
have no effect. e.g.: the slave device roce status remain unchanged.
Therefore disable it and add an error message.
Enable or disable roce of the master device affect both master and slave
devices.

Fixes: cc9defcb ("net/mlx5: Handle "enable_roce" devlink param")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

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

@@ -273,6 +273,10 @@ static int mlx5_devlink_enable_roce_validate(struct devlink *devlink, u32 id,
 		NL_SET_ERR_MSG_MOD(extack, "Device doesn't support RoCE");
 		return -EOPNOTSUPP;
 	}
+	if (mlx5_core_is_mp_slave(dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Multi port slave device can't configure RoCE");
+		return -EOPNOTSUPP;
+	}
 
 	return 0;
 }