mm: Show correct reliable_user_used if PAGE_SIZE is not 4K

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4SK3S


CVE: NA

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Previous reliable_user_used was wrong if PAGE_SIZE is not 4K because this
num was calculated by 4 * reliable_user_used_nr_page.

Now reliable_user_used is calculated by (PAGE_SHIFT - 10) *
reliable_user_used_nr_page.

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng <Wang&lt;wangkefeng.wang@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>