hwc: Avoid MDP draw if prepare is not successful.

If #AppLayers are 0 or exceed MAX_NUM_APP_LAYERS
return early from MDP draw.

Change-Id: I834c7b04a295fbd9b98374cade880992d995ad1f
diff --git a/libhwcomposer/hwc_mdpcomp.h b/libhwcomposer/hwc_mdpcomp.h
index 520c176..850e242 100644
--- a/libhwcomposer/hwc_mdpcomp.h
+++ b/libhwcomposer/hwc_mdpcomp.h
@@ -43,6 +43,8 @@
     int prepare(hwc_context_t *ctx, hwc_display_contents_1_t* list);
     /* draw */
     virtual bool draw(hwc_context_t *ctx, hwc_display_contents_1_t *list) = 0;
+    //Reset values
+    void reset();
     /* dumpsys */
     void dump(android::String8& buf, hwc_context_t *ctx);
     bool isGLESOnlyComp() { return (mCurrentFrame.mdpCount == 0); }
@@ -54,7 +56,6 @@
     /* Initialize MDP comp*/
     static bool init(hwc_context_t *ctx);
     static void resetIdleFallBack() { sIdleFallBack = false; }
-    static void reset() { sHandleTimeout = false; };
     static bool isIdleFallback() { return sIdleFallBack; }
 
 protected:
@@ -250,6 +251,7 @@
     static bool sEnable4k2kYUVSplit;
     /* Overlap layer index */
     int mOverlapIndex;
+    bool mModeOn; // if prepare happened
     bool allocSplitVGPipesfor4k2k(hwc_context_t *ctx, int index);
 };