While PCAP_RTC_DAY_MASK is set to 0x3ffff, it is very unlikely to be
correct as this ends in june 1992, before the product even existed. It is
more likely to be a 14-bit day counter. The next product in the family (the
mc13xxx) has a 15-bit day counter.

The same issue is seen with PCAP_RTC_TOD_MASK which only has 65535 seconds
and falls short of the necessary 86400 seconds.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>