rtc: rv3028: remove RTC_VL_CLR handling

Remove RTC_VL_CLR handling because it is a disservice to userspace as it
removes the important information that the RTC data is invalid. This may
lead userspace to set an invalid system time later on.

Link: https://lore.kernel.org/r/20191214220259.621996-13-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-rv3028.c

@@ -438,12 +438,6 @@ static int rv3028_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 
 		return 0;
 
-	case RTC_VL_CLR:
-		ret = regmap_update_bits(rv3028->regmap, RV3028_STATUS,
-					 RV3028_STATUS_PORF, 0);
-
-		return ret;
-
 	default:
 		return -ENOIOCTLCMD;
 	}