Shorten the zen supertoast visible duration.

Bug:16215680
Change-Id: I7ac8e9637b7bf8eae55b0902c60ddc9d513f20a3
diff --git a/packages/SystemUI/res/values/config.xml b/packages/SystemUI/res/values/config.xml
index 8267846..13170ad 100644
--- a/packages/SystemUI/res/values/config.xml
+++ b/packages/SystemUI/res/values/config.xml
@@ -244,6 +244,6 @@
     <integer name="zen_toast_animation_duration">500</integer>
 
     <!-- Zen toast visibility duration -->
-    <integer name="zen_toast_visible_duration">2000</integer>
+    <integer name="zen_toast_visible_duration">500</integer>
 </resources>