qmimodem: voicecall: Implement active call hangup

hangup_active iterates the current list of calls, looking for the first
active call and then calls release_specific.  This then sets up the
parameters for a call to QMI_VOICE_END_CALL, with the only parameters
being the call-id.

end_call_cb will then be called and will parse out the call-id and check
for success.
2 files changed