The EOZ9 RTC has a similar register interface like the MCP7940M (and
quite some other I2C RTCs). This commit:
* Extracts the generic parts from MCP7940M and moves it into a generic
i2c-rtc driver.
* Uses the new i2c-rtc for the MCP7940M.
* Uses the new i2c-rtc for the new Abracom EOZ9.
