rtc: max77686: Fix max77686_rtc_read_alarm() return value

The function is always returning zero even in case of failures since
the ret value was not propagated to the callers. Fix the error path.

Reported-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Andi Shyti <andi.shyti@samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-max77686.c

@@ -235,7 +235,7 @@ static int max77686_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
 out:
 	mutex_unlock(&info->lock);
-	return 0;
+	return ret;
 }
 
 static int max77686_rtc_stop_alarm(struct max77686_rtc_info *info)