cgroup: remove duplicate code in find_css_set()

The list head res->tasks gets initialized twice in find_css_set().

Signed-off-by: Li Zefan <[e-mail]>
Acked-by: Paul Menage <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/cgroup.c

···
 	/* Link this cgroup group into the list */
 	list_add(&res->list, &init_css_set.list);
 	css_set_count++;
-	INIT_LIST_HEAD(&res->tasks);
 	write_unlock(&css_set_lock);
 
 	return res;