mm: mem_reliable: Show reliable meminfo

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8USBA


CVE: NA

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Add reliable memory info in /proc/meminfo:

- ReliableTotal: total reliable memory size
- ReliableUsed: used reliable memory size
- ReliableShmem: reliable memory used by shmem
- FileCache: memory usage of page cache
- ReliableFileCache: reliable memory usage of page cache

Signed-off-by: Ma Wupeng <mawupeng1@huawei.com>