drm/amd/display: implement lttpr logic

drm/amd/display: implement lttpr logic

1-If at least one repeater is present in the link and we are in non
transparent mode, perform clock recovery then channel equalization
with all repeaters one by one before training DPRX.

2-Mark the end of LT with a repeater by setting training pattern 0
at the end of channel equalization with each repeater.

Signed-off-by: abdoulaye berthe <abdoulaye.berthe@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>