Where before there was a single sleep timer menu option which handled
initiating/ cancelling a sleep timer as well as setting the default duration,
now there is one menu option to either start or cancel a sleep timer and
another to set the default duration that will be used for future sleep timers.
Change-Id: Ibea3711ec6406845ff5d0c0568fe5d1739eb8deb
Reviewed-on: http://gerrit.rockbox.org/201
Reviewed-by: Nick Peskett <rockbox@peskett.co.uk>
10d8717e94