drm/amd/display: Fixed corruption on 4K tvs

[WHY]
When on the desktop freesync is not enabled,
doing a frame stretch causes the TV to display
undesired output.

[HOW]
By changing the logic so that when ever fresync
is supported the TV is notified we are in fressync
instead on a non fresync state.

Signed-off-by: Harry VanZyllDeJong <hvanzyll@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>