drm/amd/display: Handle link loss interrupt better

drm/amd/display: Handle link loss interrupt better

[Why]
Link loss currently only retrains and re-enables the stream.  This can
cause issues for some sinks.

[How]
When link loss occurs, the link and stream(s) should be completely
disabled and then reenabled.

Signed-off-by: Aric Cyr <aric.cyr@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>