SF: Avoid wormhole clear for BLIT calls

Do not call GPU clear from SF when composition
type is BLIT as it'll be taken care in HAL.

Change-Id: Ia613eb9b824c6484ecc8c8fa4ee883545d8541b8
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index c7567bd..e406744 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1847,8 +1847,12 @@
 
             // screen is already cleared here
             if (!region.isEmpty()) {
-                // can happen with SurfaceView
-                drawWormhole(hw, region);
+                if (cur != end) {
+                    if (cur->getCompositionType() != HWC_BLIT)
+                        // can happen with SurfaceView
+                        drawWormhole(hw, region);
+                } else
+                    drawWormhole(hw, region);
             }
         }