net/mlx5: use rb_entry()

To make the code clearer, use rb_entry() instead of container_of() to
deal with rbtree.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -75,7 +75,7 @@ static void mlx5_fc_stats_insert(struct rb_root *root, struct mlx5_fc *counter)
 	struct rb_node *parent = NULL;
 
 	while (*new) {
-		struct mlx5_fc *this = container_of(*new, struct mlx5_fc, node);
+		struct mlx5_fc *this = rb_entry(*new, struct mlx5_fc, node);
 		int result = counter->id - this->id;
 
 		parent = *new;