Commit 5a17f543 ("cgroup: improve css_from_dir() into css_tryget_from_dir()")
removed perf_tryget_cgroup(), so let's also remove perf_put_cgroup().
Signed-off-by: NZefan Li <lizefan@huawei.com>
Signed-off-by: NTejun Heo <tj@kernel.org>