* Unlike in AMR FR, in AMR HR incoming ONSET have to be treated
  differently depending on whether we've recently sent SID UPDATE or
  EMPTY frame. Split ST_SID_U FSM state into 2 states to accommodate for
  that and make sure that additional states specific to AMR HR are not
  used for AMR FR.

* Avoid sending E_VOICE and E_SID_U in corresponding states
  as those do not initiate FSM state transitions anyway. This decrease
  extra load from FSM signalling which otherwise would be triggered on
  per-frame basis.

* Introduce separate signal for SID First P1 -> P2 transition to avoid
  confusion with E_COMPL and E_SID_U initiated transitions from P1
  state.

* Don't init DTX FSM for SDCCH channels.

Change-Id: I229ba39a38a223fada4881fc9aca35d3639371f8
Related: OS#1801