[Why]
Simplify AVMUTE logic in coding

[How]
Avoid multiple calls on TMDS AVMUTE
as updated logic now demands it.
Signed-off-by: NChris Park <Chris.Park@amd.com>
Reviewed-by: NCharlene Liu <Charlene.Liu@amd.com>
Acked-by: NQingqing Zhuo <Qingqing.Zhuo@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>