Do not stop FM Radio Service during unbind using stopSelf.

During Unbind, do not kill FM Radio service. The service might restart
again and it will end up getting Media Button events starving other
eligible applications. Use explicit stopService call in FM Radio. This
calls Destroy callback resulting in proper clean up of FM Radio Service.

CRs-Fixed: 932236
Change-Id: Idf3d768e66bd4bafc7d1ef40aefa15982454889c