net/mlx5: Fix not releasing read lock when adding flow rules

If building match list fg fails and we never jumped to
search_again_locked label then the function returned without
unlocking the read lock.

Fixes: bd71b08 ("net/mlx5: Support multiple updates of steering rules in parallel")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

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

@@ -1726,6 +1726,8 @@ _mlx5_add_flow_rules(struct mlx5_flow_table *ft,
 	if (err) {
 		if (take_write)
 			up_write_ref_node(&ft->node);
+		else
+			up_read_ref_node(&ft->node);
 		return ERR_PTR(err);
 	}