net/mlx5: Fix autogroups groups num not decreasing

Autogroups groups num is increased when creating a new flow group,
but is never decreased.

Now decreasing it when deleting a flow group.

Fixes: f0d22d18 ('net/mlx5_core: Introduce flow steering autogrouped flow table')
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -436,6 +436,9 @@ static void del_flow_group(struct fs_node *node)
 	fs_get_obj(ft, fg->node.parent);
 	dev = get_dev(&ft->node);
 
+	if (ft->autogroup.active)
+		ft->autogroup.num_groups--;
+
 	if (mlx5_cmd_destroy_flow_group(dev, ft, fg->id))
 		mlx5_core_warn(dev, "flow steering can't destroy fg %d of ft %d\n",
 			       fg->id, ft->id);