msm: mdss: Correction in cyclical reading of histogram bins

The iteration condition in loop for reading histogram bin has an
error. We are essentially missing out on the value of one bin.

Change-Id: I713ad6c580374173b38cd1a1f4f8120f55cf1452
Signed-off-by: Krishna Chaitanya Parimi <cparimi@codeaurora.org>
msm: mdss: Verify histogram size before sending to user

Add check to DSPP histograms to verify that the number of pixels collected
is the same as the resolution of the region being processed.

Change-Id: I21acd1b4a25d06391c853e7495ca3fb3bb0ffef4
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>
Signed-off-by: Ping Li <quicpingli@codeaurora.org>