Fix Setting->Display always force close issue

CTS's AdminTest will change the display timeout to 5 seconds.
It will cause Setting->Display 100% force close. It has been reported in
http://code.google.com/p/android/issues/detail?id=27026 . This patch is
for solving this issue.

Change-Id: Icf4061023f040ee164d161b9db717acbc9697124