memcg: remove unused do_memsw_account in memcg1_stat_format

Since commit b25806dc("mm: memcontrol: deprecate swapaccounting=0
mode") do_memsw_account() is synonymous with
!cgroup_subsys_on_dfl(memory_cgrp_subsys), It always equals true in
memcg1_stat_format().  Remove the unused code.

Link: https://lkml.kernel.org/r/20230915105845.3199656-3-liushixin2@huawei.comSigned-off-by: Liu Shixin <liushixin2@huawei.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memcontrol.c

@@ -4113,8 +4113,6 @@ static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
 	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
 		unsigned long nr;
 
-		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
-			continue;
 		nr = memcg_page_state_local(memcg, memcg1_stats[i]);
 		seq_buf_printf(s, "%s %lu\n", memcg1_stat_names[i],
 			   nr * memcg_page_state_unit(memcg1_stats[i]));
@@ -4137,15 +4135,12 @@ static void memcg1_stat_format(struct mem_cgroup *memcg, struct seq_buf *s)
 	}
 	seq_buf_printf(s, "hierarchical_memory_limit %llu\n",
 		       (u64)memory * PAGE_SIZE);
-	if (do_memsw_account())
-		seq_buf_printf(s, "hierarchical_memsw_limit %llu\n",
-			       (u64)memsw * PAGE_SIZE);
+	seq_buf_printf(s, "hierarchical_memsw_limit %llu\n",
+		       (u64)memsw * PAGE_SIZE);
 
 	for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
 		unsigned long nr;
 
-		if (memcg1_stats[i] == MEMCG_SWAP && !do_memsw_account())
-			continue;
 		nr = memcg_page_state(memcg, memcg1_stats[i]);
 		seq_buf_printf(s, "total_%s %llu\n", memcg1_stat_names[i],
 			   (u64)nr * memcg_page_state_unit(memcg1_stats[i]));