mm/memcontrol.c: replace cgroup_memory_nokmem with mem_cgroup_kmem_disabled()

mem_cgroup_kmem_disabled() checks whether the kmem accounting is off. 
Therefore, replace cgroup_memory_nokmem with mem_cgroup_kmem_disabled(),
which is the same work in percpu.c and slab_common.c.

Link: https://lkml.kernel.org/r/20220625061844.226764-1-xiangyang3@huawei.comSigned-off-by: Xiang Yang <xiangyang3@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Souptick Joarder (HPE) <jrdr.linux@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcontrol.c

@@ -3653,7 +3653,7 @@ static int memcg_online_kmem(struct mem_cgroup *memcg)
 {
 	struct obj_cgroup *objcg;
 
-	if (cgroup_memory_nokmem)
+	if (mem_cgroup_kmem_disabled())
 		return 0;
 
 	if (unlikely(mem_cgroup_is_root(memcg)))
@@ -3677,7 +3677,7 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
 {
 	struct mem_cgroup *parent;
 
-	if (cgroup_memory_nokmem)
+	if (mem_cgroup_kmem_disabled())
 		return;
 
 	if (unlikely(mem_cgroup_is_root(memcg)))