arm64/ascend: Add hugepage flags change interface

ascend inclusion
category: feature
bugzilla: NA
CVE: NA

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Add a variable to change alloc hugepage gfp flags, and export it out.
Hugepage need to be accounted by cgroup. We use this to set ACCOUNT
flag to memory subsystem.

Signed-off-by: Weilong Chen <chenweilong@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>