msm: camera: mem: Correct cache direction

Appropriate cache direction is mandate to maintain the cache
properly. This gerrit sets the proper direction for the dma buf
based on the operation send by userspace.

Change-Id: Id71e88e79493a0adf1c29491ebc9b1986ce1288f
Signed-off-by: Pavan Kumar Chilamkurthi <pchilamk@codeaurora.org>