Revert "mm: don't do swap readahead during speculative page fault"

This reverts commit c41742ec.

Bug: 128240262
Change-Id: Ide6a3bb060fd1792c1ac5880cfc2298931ad07ed
Signed-off-by: Minchan Kim <minchan@google.com>
[dereference23: Forward port to msm-5.4]
Signed-off-by: Alexander Winkowski <dereference23@outlook.com>