drm/amd/display: Reset preferred training settings immediately

[Why & How]
In order to easily test ilr by immediately reset the preferred training settings,
fix the code to disable skip_immediate_retrain.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Solomon Chiu <solomon.chiu@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Wayne Lin <Wayne.Lin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>