According to HDMI CEC specification, an audio system can report its audio status when System Audio Mode is on, so that the TV can display the audio status of external amplifier. More details can be found in section CEC-13.15 of HDMI Specification 1.4b Bug: 80297383 Test: make; flashall; local tests Change-Id: Id71b709a62add7bf5dccb418489e200350debb8e