rtc: snvs: return error in case enable_irq_wake fails

If enable_irq_wake fails, we should return that error code so that
entering suspend fails. Otherwise we will get a WARNING along with
the hint of a unbalanced wake disable:
Unbalanced IRQ 37 wake disable
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-snvs.c

@@ -322,7 +322,7 @@ static int snvs_rtc_suspend(struct device *dev)
 	struct snvs_rtc_data *data = dev_get_drvdata(dev);
 
 	if (device_may_wakeup(dev))
-		enable_irq_wake(data->irq);
+		return enable_irq_wake(data->irq);
 
 	return 0;
 }