zram & zsmalloc: update to msm-3.7 version

* Remove old zram version in drivers/zram
* Update zram & zsmalloc to latest unchanged msm-3.7 (will
  add compatibility in separate change).

Change-Id: I05bed573cc37a5b04ff0d1ac67fbd60632b52c05
(cherry picked from commit a2ebf7415ca2bfaff46bf310ec3d79d1544eb33d)