rtc: max8997: Fix the returned value in case of error in 'max8997_rtc_read_alarm()'

In case of error, we return 0.
This is spurious and not consistent with the other functions of the driver.
Propagate the error code instead.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-max8997.c

@@ -215,7 +215,7 @@ static int max8997_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
 out:
 	mutex_unlock(&info->lock);
-	return 0;
+	return ret;
 }
 
 static int max8997_rtc_stop_alarm(struct max8997_rtc_info *info)