rtc: mv: let the core handle invalid alarms

Instead of lying to the core when the alarm is invalid, let it handle that
by returning the error.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>  (on Armada 375 DB)
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-mv.c

@@ -125,13 +125,9 @@ static int mv_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
 	/* hw counts from year 2000, but tm_year is relative to 1900 */
 	alm->time.tm_year = bcd2bin(year) + 100;
 
-	if (rtc_valid_tm(&alm->time) < 0) {
-		dev_err(dev, "retrieved alarm date/time is not valid.\n");
-		rtc_time_to_tm(0, &alm->time);
-	}
-
 	alm->enabled = !!readl(ioaddr + RTC_ALARM_INTERRUPT_MASK_REG_OFFS);
-	return 0;
+
+	return rtc_valid_tm(&alm->time);
 }
 
 static int mv_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)