net/mlx5: Fix query E-Switch capabilities

BugLink: http://bugs.launchpad.net/bugs/1540435

E-Switch capabilities should be queried only if E-Switch flow table
is supported and not only when vport group manager.

Fixes: d6666753 ("net/mlx5: E-Switch, Introduce HCA cap and E-Switch vport context")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 9bd0a185)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

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

@@ -173,7 +173,7 @@ int mlx5_query_hca_caps(struct mlx5_core_dev *dev)
 			return err;
 	}
 
-	if (MLX5_CAP_GEN(dev, vport_group_manager)) {
+	if (MLX5_CAP_GEN(dev, eswitch_flow_table)) {
 		err = mlx5_core_get_caps(dev, MLX5_CAP_ESWITCH,
 					 HCA_CAP_OPMOD_GET_CUR);
 		if (err)