net/mlx5e: Protect against non-uplink representor for encap

TC encap offload is supported only for the physical uplink
representor. Fail for non uplink representor.

Fixes: 3e621b19 ("net/mlx5e: Support TC encapsulation offloads with upper devices")
Signed-off-by: Dmytro Linkin <dmitrolin@mellanox.com>
Reviewed-by: Eli Britstein <elibr@mellanox.com>
Reviewed-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en/tc_tun.c

@@ -39,6 +39,10 @@ static int get_route_and_out_devs(struct mlx5e_priv *priv,
 			return -EOPNOTSUPP;
 	}
 
+	if (!(mlx5e_eswitch_rep(*out_dev) &&
+	      mlx5e_is_uplink_rep(netdev_priv(*out_dev))))
+		return -EOPNOTSUPP;
+
 	return 0;
 }