rtc: stop validating rtc_time in .read_time

The RTC core is always calling rtc_valid_tm after the read_time callback.
It is not necessary to call it just before returning from the callback.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-ds1307.c

@@ -437,8 +437,7 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 		t->tm_hour, t->tm_mday,
 		t->tm_mon, t->tm_year, t->tm_wday);
 
-	/* initial clock setting can be undefined */
-	return rtc_valid_tm(t);
+	return 0;
 }
 
 static int ds1307_set_time(struct device *dev, struct rtc_time *t)