ANDROID: mm: provision to add shmem pages to inactive file lru head

Commit 9975da5f ("ANDROID: mm: allow fast reclaim of shmem pages")
allows pages to add only to the tail of the inactive file lru for faster
reclaims. Extend the same to allow the pages added to the head of the
inactive file lru too. This will enable users to selectively add the
shmem file pages to head or tail of the inactive file lru.

Bug: 187798288
Change-Id: Icf167e1e3ea68257291478e1f16de678ecbf6320
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>