drm/amd/display: Fix debugfs link_settings entry

drm/amd/display: Fix debugfs link_settings entry

1. Catch invalid link_rate and link_count settings
2. Call dc interface to overwrite preferred link settings, and wait
until next stream update to apply the new settings.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>