mm: Export symbol reclaim_pages

euleros inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8T1MB?from=project-issue


CVE: NA

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Export reclaim_pages so that etmem_swap can exploit
this for memory reclamation.

In etmem swap module, it will receive a list of pages
that need to be reclaimed, sent from the user mode
program. etmem swap module will do some checks and add
appropriate candidates to folio_list, which will later
be reclaimed by reclaim_pages.

Signed-off-by: Yuchen Tang <tangyuchen5@huawei.com>