Revert "staging: zcache: fix cleancache race condition with shrinker"

This reverts commit 563ab926e4924515c0e18f3d4814756a86420ee6.
Revert "mm: implement WasActive page flag (for improving cleancache)"

This reverts commit 638bcc4534f4042604fd1cf18d8776e53f68f4a4.