[why]
A debug option is needed to temporarily force dp2 new link training
fallback method for debugging purpose.
Reviewed-by: NGeorge Shen <George.Shen@amd.com>
Acked-by: NPavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: NWenjing Liu <wenjing.liu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>