msm: display: update histogram interface for MDP5

MDP5 supports 256 histogram bins now, which is not able to be
stored in the 8 bit unsigned integer used currently. Increase
this variable to be able to accommodate it.

Change-Id: Ie62ba14cb51f3db9ab3e0b7ad94ac59827611210
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>
diff --git a/include/linux/msm_mdp.h b/include/linux/msm_mdp.h
index 1cdc434..98050ce 100644
--- a/include/linux/msm_mdp.h
+++ b/include/linux/msm_mdp.h
@@ -399,7 +399,7 @@
 	uint32_t block;
 	uint8_t frame_cnt;
 	uint8_t bit_mask;
-	uint8_t num_bins;
+	uint16_t num_bins;
 };
 
 /*