drm/amd/display: Early return when turn off a plane.

In case of two monitor connected and turn off one of the monitors,
OTG0 is locked after graphic plane off due to redundant programming
front end regs.
Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -1190,8 +1190,14 @@ static void commit_planes_for_stream(struct dc *dc,
 		}
 	}
 
-	if (surface_count == 0)
+	if (surface_count == 0) {
+		/*
+		 * In case of turning off screen, no need to program front end a second time.
+		 * just return after program front end.
+		 */
 		dc->hwss.apply_ctx_for_surface(dc, stream, surface_count, context);
+		return;
+	}
 
 	/* Lock pipes for provided surfaces, or all active if full update*/
 	for (i = 0; i < surface_count; i++) {