rtc: cros-ec: let the core handle rtc range

Let the rtc core check the date/time against the RTC range.

Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Link: https://lore.kernel.org/r/20191016201414.30934-2-alexandre.belloni@bootlin.com


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