defconfig: Enable CONFIG_BALANCE_ANON_FILE_RECLAIM for sm8150

Swapping anonymous pages out to memory can be efficient enough
to justify treating anonymous and file backed pages equally.

Change-Id: Idc663426ac1e16431253e3e95365dad6bf4d3b04
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>