ANDROID: mm: Add vendor hook in pagecache_get_page()

Add a vendor hook for pagecache hit/miss and other
vendor specific functions.

 Conflicts:
	drivers/android/vendor_hooks.c
	include/trace/hooks/mm.h
	mm/filemap.c

Bug: 174088128
Bug: 172987241
Signed-off-by: Chiawei Wang <chiaweiwang@google.com>
Change-Id: Ie9f14a69a86b8ed81de766e44e30f2eba1d9bd84
(cherry picked from commit db158b4a)
Signed-off-by: Hailong Liu <liuhailong@oppo.com>