drm/amd/display: Re-enable Vsync Interrupts for Gradual Refresh Ramp

- Make sure Vsync interrupts are disabled in static screen case
  and enabled when not to save power
- Create no_static_for_external_dp debug option

Signed-off-by: Amy Zhang <Amy.Zhang@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 3e2ed3d..93aff82 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -188,6 +188,7 @@ struct dc_debug {
 	bool disable_dmcu;
 	bool disable_psr;
 	bool force_abm_enable;
+	bool no_static_for_external_dp;
 };
 
 struct dc {