mm: update outdated comments for removed scan_swap_map_slots()

The function scan_swap_map_slots() was removed in commit 0ff67f990bd4
("mm, swap: remove swap slot cache").

The three comments referencing it simply noted that ->flags can be updated
non-atomically by scan_swap_map_slots() to justify a data_race()
annotation. Since the function no longer exists, drop the parenthetical
reference while keeping the data_race() justification intact: ->flags can
still be updated non-atomically by other paths (e.g., swapoff clearing
SWP_WRITEOK).

Assisted-by: unnamed:deepseek-v3.2 coccinelle
Link: https://lkml.kernel.org/r/20260321105814.7053-1-kexinsun@smail.nju.edu.cn
Signed-off-by: Kexin Sun <kexinsun@smail.nju.edu.cn>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Julia Lawall <julia.lawall@inria.fr>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>