rtc: cpcap: set range

The CPCAP rtc is a 14bit day counter plus a 17bit seconds counter.

Note that this failed on Nov 10 2014 so it is very likely this driver as
never been used since.

Link: https://lore.kernel.org/r/20200306015703.42101-2-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>