clocksource: sh_mtu2: Add clk_prepare/unprepare support

Prepare the clock at probe time, as there is no other appropriate place
in the driver where we're allowed to sleep.

Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/sh_mtu2.c

@@ -313,13 +313,18 @@ static int sh_mtu2_setup(struct sh_mtu2_priv *p, struct platform_device *pdev)
 		goto err1;
 	}
 
+	ret = clk_prepare(p->clk);
+	if (ret < 0)
+		goto err2;
+
 	ret = sh_mtu2_register(p, (char *)dev_name(&p->pdev->dev),
 			       cfg->clockevent_rating);
 	if (ret < 0)
-		goto err2;
+		goto err3;
 
 	return 0;
-
+ err3:
+	clk_unprepare(p->clk);
  err2:
 	clk_put(p->clk);
  err1: