msm: camera: add fields to msm_stats_buf for cache operations.

Add a couple of fields to the msm_stats_buf structure
for cache coherence support on stats buffers from
user-space.

Change-Id: I3553fcf6359e4e748eb309d4a0a5979999d96f09
Signed-off-by: Ankit Premrajka <ankitp@codeaurora.org>