mm: Show correct reliable pagecache size

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


CVE: NA

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Show corrent reliable pagecache size if /proc/meminfo if
memory reliable and pagecache use reliable memory is enabled.

Fixes: 9f07eb30 ("mm: Add space after ReliableFileCache")
Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>