Improve shadow tessellation performance

- Tune and simplify shadow parameters
- Remove additional inner rings
- Improve polygon ray casting algorithm

Change-Id: If0f28b2d66ae0480b675942bb65e8fcd2864425d
diff --git a/libs/hwui/Caches.cpp b/libs/hwui/Caches.cpp
index 1d58d96..f02e591 100644
--- a/libs/hwui/Caches.cpp
+++ b/libs/hwui/Caches.cpp
@@ -705,8 +705,8 @@
     propertyDirtyViewport = false;
     propertyEnable3d = false;
     propertyCameraDistance = 1.0f;
-    propertyAmbientShadowStrength = 0x3f;
-    propertySpotShadowStrength = 0x3f;
+    propertyAmbientShadowStrength = 25;
+    propertySpotShadowStrength = 25;
 
     propertyLightPosXScale = 0.5f;
     propertyLightPosYScale = 0.0f;