Do less work on configuration change.

Change-Id: I8c657ba8913b4be288cb0979897479a1db33aacf
Fixes: 29625463
diff --git a/packages/SystemUI/src/com/android/systemui/volume/VolumeDialog.java b/packages/SystemUI/src/com/android/systemui/volume/VolumeDialog.java
index af6fec2..2094c08 100644
--- a/packages/SystemUI/src/com/android/systemui/volume/VolumeDialog.java
+++ b/packages/SystemUI/src/com/android/systemui/volume/VolumeDialog.java
@@ -973,6 +973,7 @@
                 mDialog.dismiss();
                 mZenFooter.cleanup();
                 initDialog();
+                mDensity = density;
             }
             updateWindowWidthH();
             mSpTexts.update();