kmsmuxingpipeline: Remove unrequired function

Change-Id: Ia9cbeafd5bbf7ce3144b69910167990bc93f959f
kmsmuxingpipeline: Free resources on destroy

Change-Id: I0ad135d499595b4c47f8e2f23558a1bf4af76c11
kmsmuxingpipeline: Add helpful functions

Change-Id: Iafa43102eecea205e4abd47def47fb825b5a9580