Add support for setting the chip address offset mask to EEPROM sumulator
and add tests to test it.

Signed-off-by: Robert Beckett <bob.beckett@collabora.com>
Series-to: u-boot@lists.denx.de
Series-cc: Robert Beckett <bob.beckett@collabora.com>
Cover-letter:
i2c: add support for offset overflow in to chip address
Add support for devices that can overflow the offset in to the chip
address. This makes the devices effectively steal consecutive chip
addresses.

Also improve i2c testing and add new test for this new addressing mode.
END