hwc: fix shaking issue due to swap rect in mdp3

we should count the same dirtyRect and displayRect
min 3 times before enabling sawpRect feature.

Change-Id: I58524f0d1b9265e052a796f649e737765a1f8404
diff --git a/libhwcomposer/hwc_copybit.h b/libhwcomposer/hwc_copybit.h
index 4442afc..eaf015f 100644
--- a/libhwcomposer/hwc_copybit.h
+++ b/libhwcomposer/hwc_copybit.h
@@ -72,11 +72,14 @@
     /* framebuffer cache*/
     struct FbCache {
       hwc_rect_t  FbdirtyRect[NUM_RENDER_BUFFERS];
+      hwc_rect_t  FbdisplayRect[NUM_RENDER_BUFFERS];
       int FbIndex;
       FbCache();
       void reset();
-      void insertAndUpdateFbCache(hwc_rect_t dirtyRect);
-      int getUnchangedFbDRCount(hwc_rect_t dirtyRect);
+      void insertAndUpdateFbCache(hwc_rect_t dirtyRect,
+                               hwc_rect_t displayRect);
+      int getUnchangedFbDRCount(hwc_rect_t dirtyRect,
+                             hwc_rect_t displayRect);
     };
 
     // holds the copybit device