Don't update volume in AudioService when SAM is on and ARC is off

This prevents volume from changing on TV panels when a connected
amplifier sends <Report Audio Status>.

Test: manual with Isto and Atom
atest com.android.server.hdmi.HdmiCecLocalDeviceTvTest#handleReportAudioStatus_SamOnArcOff_noVolumeChange
Bug: 182369742

Change-Id: I412ee9d5b1ba7aab382e73deab8ac19546175842