rtc: coh901331: fix a missing check of clk_prepare

clk_prepare() could fail, so let's check its status and if it fails
return its error code upstream.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-coh901331.c

@@ -235,9 +235,13 @@ static int coh901331_suspend(struct device *dev)
 
 static int coh901331_resume(struct device *dev)
 {
+	int ret;
 	struct coh901331_port *rtap = dev_get_drvdata(dev);
 
-	clk_prepare(rtap->clk);
+	ret = clk_prepare(rtap->clk);
+	if (ret)
+		return ret;
+
 	if (device_may_wakeup(dev)) {
 		disable_irq_wake(rtap->irq);
 	} else {