net/mlx5e: fix double free in mlx5e_destroy_flow_table

In function accel_fs_tcp_create_groups(), when the ft->g memory is
successfully allocated but the 'in' memory fails to be allocated, the
memory pointed to by ft->g is released once. And in function
accel_fs_tcp_create_table, mlx5e_destroy_flow_table is called to release
the memory pointed to by ft->g again. This will cause double free problem.

Fixes: c062d52a ("net/mlx5e: Receive flow steering framework for accelerated TCP flows")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/fs_tcp.c

@@ -190,6 +190,7 @@ static int accel_fs_tcp_create_groups(struct mlx5e_flow_table *ft,
 	in = kvzalloc(inlen, GFP_KERNEL);
 	if  (!in || !ft->g) {
 		kfree(ft->g);
+		ft->g = NULL;
 		kvfree(in);
 		return -ENOMEM;
 	}