mm: memcg: export workingset refault stats for cgroup v1

mm: memcg: export workingset refault stats for cgroup v1

Workingset refault stats are important and useful metrics to measure how
well reclaimer and swapping work and how healthy the services are, but
they are just available for cgroup v2.  There are still plenty users with
cgroup v1, export the stats for cgroup v1.

Link: https://lkml.kernel.org/r/20220816185801.651091-1-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>