Revert "android/lowmemorykiller: Account for total_swapcache_pages"

This reverts commit 6ae6c93d5052b50b2285cdaa04ec1399e59930d8.
Revert "android: lowmemorykiller: add lmk parameters tunning code."

This reverts commit 4878253cf1a34c19596c665f045e7b73afc8783b.
android/lowmemorykiller: Account for total_swapcache_pages

The lowmemorykiller relies on NR_FILE_PAGES when measureing
the amount of reclaimable memory in the system.
However when swap is enabled swap cache pages are counted
in NR_FILE_PAGES, and swap cache pages aren't as reclaimable
in low memory as file cache pages. Therefore a large swap
cache can result in the lowmemorykiller not running and
an OOM occuring.

In order to ensure the lowmemorykiller properly evaluates the
amount of reclaimable memory don't count the swap cache pages.

Change-Id: I38239283e572f814b277c718eaf6be7f92abacbb
Signed-off-by: Liam Mark <lmark@codeaurora.org>