net/mlx5: DR, fix memory leak in mlx5dr_cmd_create_reformat_ctx

when mlx5_cmd_exec failed in mlx5dr_cmd_create_reformat_ctx, the memory
pointed by 'in' is not released, which will cause memory leak. Move memory
release after mlx5_cmd_exec.

Fixes: 1d918647 ("net/mlx5: DR, Add direct rule command utilities")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>