CEC: Send <Give System Audio Mode> regardless of TV's setting.

When TV is brought back out of standby, it should send <Give System Audio Mode>
to audio receiver so that TV recovers system audio mode.
Current implementation sends <Give System Audio Mode> only when setting is "ON".
In order to fix this, this change sends <Give System Audio Mode>
regardless of TV's setting and update system audio mode according to
response of <Give System Audio Mode>.

Bug: 18267467
Change-Id: I2c3c05347c6f2a7a3a5e3772e4e26c77156eb740