drm: rcar-du: fix incorrect return in rcar_du_crtc_cleanup()

The rcar_du_crtc_cleanup() function has a void return type, but
incorrectly uses a return statement with a call to drm_crtc_cleanup(),
which also returns void.

Remove the return statement to ensure proper function semantics.
No functional change intended.

Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://patch.msgid.link/20251017191634.1454201-1-alok.a.tiwari@oracle.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Author: aloktiwa

drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c

@@ -994,7 +994,7 @@ static void rcar_du_crtc_cleanup(struct drm_crtc *crtc)
 
 	rcar_du_crtc_crc_cleanup(rcrtc);
 
-	return drm_crtc_cleanup(crtc);
+	drm_crtc_cleanup(crtc);
 }
 
 static void rcar_du_crtc_reset(struct drm_crtc *crtc)