cgroup: simplify proc_cgroup_show()

Use the ONE macro instead of REG, and we can simplify proc_cgroup_show().

Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 51958d0..77a1d37 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -37,7 +37,8 @@
 extern int cgroupstats_build(struct cgroupstats *stats,
 				struct dentry *dentry);
 
-extern int proc_cgroup_show(struct seq_file *, void *);
+extern int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+			    struct pid *pid, struct task_struct *tsk);
 
 /* define the enumeration of all cgroup subsystems */
 #define SUBSYS(_x) _x ## _cgrp_id,