rtc: rzn1: Report maximum alarm limit to rtc core

RZN1 only supports alarms up to one week in the future.
Report the limit to the RTC core and use the reported limit
to validate the requested alarm time when setting it.

Cc: Brian Norris <briannorris@chromium.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230817225537.4053865-8-linux@roeck-us.net


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