drm/amd/display: Add debug param to force dio disable

[WHY]
At the moment, some tests are failing because cur_link_settings is
invalid. As a workaround, add an option to force dio disable.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>