audio: Fix mute state handling issue for HDMI-CEC

Issue:
Some Audio Systems (HDMI-CEC devices) in the market are designed to
"maintain mute status while decreasing volume."
When volume of an Audio System is decreased during mute,
the volume UI incorrectly shows unmute state,
even though the Audio System remains muted.

Root Cause:
The AudioFramework automatically unmutes when it receives any
volume setting command, even when HDMI-CEC Report Audio Status
from the Audio System indicates the device is still muted.

Solution:
Modify the AudioFramework to not update the mute state
when processing volume settings for HDMI-CEC Report Audio Status.

Bug: 410740830
Test: manual - press the volume key on the HDMI-CEC device remote
control while audio is muted
Flag: EXEMPT bugfix

Change-Id: Idcc740600e993cf99908ff92a135191fc23147ac
Signed-off-by: Tomoki Yonezawa <Tomoki.Yonezawa@sony.com>