SystemUI: Fix alarm icon

* The icon was initially shown but not again after a reboot
* Reason is, that the user setup isn't completed again
  and therefore the variable mCurrentUserSetup will never
  hold true again
* Fix this by calling onUserSetupChanged once manually to
  get a proper initial state
* Similar code exists in other places in SystemUI as well:
  NavigationBar.java, NetworkControllerImpl.java, ...
  -> Looks like this one was forgotten

Change-Id: I02295a70a82696e7c0c6ade93c96e661140886f0