Fix memory leak in pie controller

Bug: 7622218
Change-Id: Iaab96008a4f4b506bb0be98f489af9120d607251
diff --git a/src/com/android/camera/PieController.java b/src/com/android/camera/PieController.java
index 5ccab5e..cc38881 100644
--- a/src/com/android/camera/PieController.java
+++ b/src/com/android/camera/PieController.java
@@ -63,6 +63,7 @@
 
     public void initialize(PreferenceGroup group) {
         mRenderer.clearItems();
+        mPreferenceMap.clear();
         setPreferenceGroup(group);
     }