rtc: rs5c348: let the core handle invalid time

Returning a valid time when the time is invalid is a bad practice, because
then userspace is not able to react on the information. Also, it doesn't
make sense to return epoch because it is already the default time.

Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-rs5c348.c

···
 	tm->tm_year = bcd2bin(rxbuf[RS5C348_REG_YEAR]) +
 		((rxbuf[RS5C348_REG_MONTH] & RS5C348_BIT_Y2K) ? 100 : 0);
 
-	if (rtc_valid_tm(tm) < 0) {
-		dev_err(&spi->dev, "retrieved date/time is not valid.\n");
-		rtc_time_to_tm(0, tm);
-	}
-
 	return 0;
 }