Fix blur scale (#1861)

Fixed empirically. Probably needs more tuning though.
diff --git a/lottie/src/main/java/com/airbnb/lottie/model/layer/BaseLayer.java b/lottie/src/main/java/com/airbnb/lottie/model/layer/BaseLayer.java
index bc496da..437da4b 100644
--- a/lottie/src/main/java/com/airbnb/lottie/model/layer/BaseLayer.java
+++ b/lottie/src/main/java/com/airbnb/lottie/model/layer/BaseLayer.java
@@ -601,7 +601,7 @@
     if (blurMaskFilterRadius == radius) {
       return blurMaskFilter;
     }
-    blurMaskFilter = new BlurMaskFilter(radius, BlurMaskFilter.Blur.NORMAL);
+    blurMaskFilter = new BlurMaskFilter(radius / 2f, BlurMaskFilter.Blur.NORMAL);
     blurMaskFilterRadius = radius;
     return blurMaskFilter;
   }