CEC: Fix cect_GiveSystemAudioModeStatus test

While waiting for <REPORT_POWER_STATUS> message, we were discarding
the <GIVE_SYSTEM_AUDIO_STATUS> message received from device.
So instead of waiting for transition just validate wakefullness.

Bug: 218500266
Test: atest HdmiCecSystemAudioControlTest#cect_GiveSystemAudioModeStatus
Change-Id: Ifeefc1b51314b17356dd588dc5e7d96e3b1860d4
2 files changed