[pvr] remove a lot of unused methods and some unused code
[pvr] don't queue the channel switch manually, reuse the method for it
[pvr] don't remove a pending job from the queue until it has been
completed, otherwise we may unnecessarily queue similar jobs
[pvr] remove some unneeded locks
[pvr] no need to assign a variable twice
[pvr] reduce variable scope
[pvr] minor refactoring to get rid of almost unused return variable