ANDROID: mm: Reset unused page flag bits on free

Add vendor hook to reset unused bits in page flags to zero when
releasing a page. This reserves space for OEMs to define
vendor-specific features.

Bug: 420361650
Bug: 426115925
Bug: 432441782
Change-Id: Ife2b96de64eea670d257f1a8d9fd07d16c0ddc83
Signed-off-by: Yang Yang <yang.yang@vivo.com>
(cherry picked from commit 8fb77f6f)
Signed-off-by: ying zuxin <11154159@vivo.com>
(cherry picked from commit 6eca3e3f)