clocksource/drivers/renesas-ostm: Use DIV_ROUND_CLOSEST() helper

Use the DIV_ROUND_CLOSEST() helper instead of open-coding the same
operation.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/renesas-ostm.c

@@ -221,7 +221,7 @@ static int __init ostm_init(struct device_node *np)
 	}
 
 	rate = clk_get_rate(ostm_clk);
-	ostm->ticks_per_jiffy = (rate + HZ / 2) / HZ;
+	ostm->ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
 
 	/*
 	 * First probed device will be used as system clocksource. Any