drm: rcar-du: Use 1000 to avoid misunderstanding in rcar_du_dpll_divider()

It is difficult to understand its scale if number has many 0s.
This patch uses "* 1000" to avoid it in rcar_du_dpll_divider().
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

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

@@ -132,7 +132,7 @@ static void rcar_du_dpll_divider(struct rcar_du_crtc *rcrtc,
 
 				output = input * (n + 1) / (m + 1)
 				       / (fdpll + 1);
-				if (output >= 400000000)
+				if (output >= 400 * 1000 * 1000)
 					continue;
 
 				diff = abs((long)output - (long)target);