German: more general rington picker dialog title

This title is commonly used in the dialog for picking up ringtones
and notification tone in Settings app and alarm tone in Alarm clock app.
"Ringtones" (Klingeltöne) is associated to an incomming call,
at least in German. Here we change it to be more general for all occurrences.

Change-Id: I47ee1b3deeced21d40447f99330cea833675e15e