Fix 2260199 - App icons placed in folder widget are doubled after rebooting phone.

I don't know why I did this piecemeal instead of just fixing it for widgets items and folders all at
once.
diff --git a/src/com/android/launcher2/LauncherModel.java b/src/com/android/launcher2/LauncherModel.java
index a796831..262190d 100644
--- a/src/com/android/launcher2/LauncherModel.java
+++ b/src/com/android/launcher2/LauncherModel.java
@@ -616,6 +616,7 @@
 
                 mItems.clear();
                 mAppWidgets.clear();
+                mFolders.clear();
 
                 final Cursor c = contentResolver.query(
                         LauncherSettings.Favorites.CONTENT_URI, null, null, null, null);