ascend: mm: Add MAP_ALIGN flag to map aligned va

ascend inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4UR5Y


CVE: NA

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svm module use svm_get_unmapped_area ops to map an aligned va, which
used by mapping l2buf memory. The svm_get_unmapped_area use a lot of
duplicated codes, we add MAP_ALIGN to adjust mapinfo alignmask.

Signed-off-by: Lijun Fang <fanglijun3@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>