net/mlx5e: Make function mlx5i_grp_sw_update_stats() static

Fixes the following sparse warning:

drivers/net/ethernet/mellanox/mlx5/core/ipoib/ipoib.c:119:6: warning:
 symbol 'mlx5i_grp_sw_update_stats' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -116,7 +116,7 @@ static void mlx5i_cleanup(struct mlx5e_priv *priv)
 	/* Do nothing .. */
 }
 
-void mlx5i_grp_sw_update_stats(struct mlx5e_priv *priv)
+static void mlx5i_grp_sw_update_stats(struct mlx5e_priv *priv)
 {
 	struct mlx5e_sw_stats s = { 0 };
 	int i, j;