mm/memcg: fix obsolete function name in mem_cgroup_protection()

mm/memcg: fix obsolete function name in mem_cgroup_protection()

Commit 45c7f7e1ef17 ("mm, memcg: decouple e{low,min} state mutations from
protection checks") changed the function name but not the corresponding
comment.

Link: https://lkml.kernel.org/r/20230727115934.657787-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>