rtc: ds2404: set range

The real-time clock is a 5-byte binary counter. It is incremented 256 times
per second. The least significant byte is a count of fractional seconds.
The upper four bytes are a count of seconds. The realtime clock can
accumulate 136 years of seconds before rolling over.

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