fix [2225964] Android runtime restarted in surfaceflinger/BlurFilter.cpp

crash was due to an unintialized variable, which caused the wrong bluring
format to be used and caused a memory overrrun.
diff --git a/libs/surfaceflinger/LayerBlur.cpp b/libs/surfaceflinger/LayerBlur.cpp
index 744f2e9..5fd7904 100644
--- a/libs/surfaceflinger/LayerBlur.cpp
+++ b/libs/surfaceflinger/LayerBlur.cpp
@@ -40,9 +40,10 @@
 
 LayerBlur::LayerBlur(SurfaceFlinger* flinger, DisplayID display,
         const sp<Client>& client, int32_t i)
-: LayerBaseClient(flinger, display, client, i), mCacheDirty(true),
-mRefreshCache(true), mCacheAge(0), mTextureName(-1U), 
-mWidthScale(1.0f), mHeightScale(1.0f)
+    : LayerBaseClient(flinger, display, client, i), mCacheDirty(true),
+          mRefreshCache(true), mCacheAge(0), mTextureName(-1U),
+          mWidthScale(1.0f), mHeightScale(1.0f),
+          mBlurFormat(GGL_PIXEL_FORMAT_RGB_565)
 {
 }