hwc: Partial Update for MDP3 targets

Enable partial update for MDP3 targets.
Use computed ROI of mdpcomp in copybit
to avoid composition of layers outside ROI.

Change-Id: I4b23fd48cac814f8c35a3c01253dca8c297036f9
diff --git a/libhwcomposer/hwc_utils.h b/libhwcomposer/hwc_utils.h
index cae22f1..3d97319 100644
--- a/libhwcomposer/hwc_utils.h
+++ b/libhwcomposer/hwc_utils.h
@@ -596,6 +596,8 @@
     qhwc::PtorInfo mPtorInfo;
     //Running in Thermal burst mode
     bool mThermalBurstMode;
+    //Layers out of ROI
+    bool copybitDrop[MAX_NUM_APP_LAYERS];
 };
 
 namespace qhwc {