mm: do some clean up of accounting ReliableTaskUsed

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4PM0X


CVE: NA

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Clean up redundant code of accounting ReliableTaskUsed.

Signed-off-by: Peng Wu <wupeng58@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>