ANDROID: mm: export vm_normal_folio_pmd to allow vendors to implement simplified smaps

The current process smaps operation is time-consuming. Exporting the
vm_normal_folio_pmd function enables vendors to provide a more efficient and simplified version of smaps.

Bug: 427633539
Bug: 430182268
Bug: 434600944
Change-Id: I7710f5d1656a9f7a4ae883aefc93135c93e637b5
Signed-off-by: yipeng xiang <yipengxiang@honor.corp-partner.google.com>
(cherry picked from commit f18e354a)
(cherry picked from commit 465500c4)