Settings: Fix notification light app hint

* The old code doesn't work when the entry in the database is not
  available, because it will cause parsePackageList() to return false,
  resulting in no execution of the code taking care of displaying the hint
* Move the hint to a new function and call it at the appropriate places
  to display the hint when no entry to the database was ever made

Thanks to @mikeioannina for noticing the missing hint

Change-Id: Ie3fb39cfa7e7b04a3536f98e93e2168d7367961d