mm/sharepool: Add meminfo_alloc_sum_byKB and meminfo_alloc_sum.

hulk inclusion
category: other
bugzilla: https://gitee.com/openeuler/kernel/issues/I6ET9W



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Add meminfo_alloc_sum_byKB and meminfo_alloc_sum, and
delete duplicate or similar code.

Signed-off-by: Xu Qiang <xuqiang36@huawei.com>