rtc: sc27xx: stop validating rtc_time in .read_time

rtc_time64_to_tm never generates an invalid tm. It is not necessary to
validate it. Also, the RTC core is always calling rtc_valid_tm after the
read_time callback.
Reviewed-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-sc27xx.c

@@ -376,7 +376,7 @@ static int sprd_rtc_read_time(struct device *dev, struct rtc_time *tm)
 		return ret;
 
 	rtc_time64_to_tm(secs, tm);
-	return rtc_valid_tm(tm);
+	return 0;
 }
 
 static int sprd_rtc_set_time(struct device *dev, struct rtc_time *tm)