arm64: defconfig: Enable memory configs on genericarmv8-64

Enable CONFIG_VM_EVENT_COUNT_CLEAN_PAGE_RECLAIM and
CONFIG_BALANCE_ANON_FILE_RECLAIM on genericarmv8-64.

Change-Id: I9810575dcabd14a2e39c2e08d502e3213877ed69
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>