shmem: mem_reliable: Alloc shmem from reliable region

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


CVE: NA

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This feature depends on the overall memory reliable feature.
When the shared memory reliable feature is enabled, the pages
used by the shared memory are allocated from the mirrored
region by default.

Signed-off-by: Zhou Guanghui <zhouguanghui1@huawei.com>