net/mlx5: E-Switch, Reduce ingress acl modify metadata stack usage

Fix the following compiler warning:
In function ‘esw_vport_add_ingress_acl_modify_metadata’:
the frame size of 1084 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Since the structure is never written to, we can statically allocate
it to avoid the stack usage.

Fixes: 7445cfb116 ("net/mlx5: E-Switch, Tag packet with vport number in VF vports and uplink ingress ACLs")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Reviewed-by: Jianbo Liu <jianbol@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1785,8 +1785,8 @@ static int esw_vport_add_ingress_acl_modify_metadata(struct mlx5_eswitch *esw,
 						     struct mlx5_vport *vport)
 {
 	u8 action[MLX5_UN_SZ_BYTES(set_action_in_add_action_in_auto)] = {};
+	static const struct mlx5_flow_spec spec = {};
 	struct mlx5_flow_act flow_act = {};
-	struct mlx5_flow_spec spec = {};
 	int err = 0;
 
 	MLX5_SET(set_action_in, action, action_type, MLX5_ACTION_TYPE_SET);