i2c: core: fixed a bug in the transfer init

__i2c_transfer:
	Fixed a bug that would setup a faulty transfer by passing the
	wrong amount messages to the I2C bus transfer routine
	(i2c_bus::xfer).

init:
	Fixed an I2C initialisation bug for AVR chips. The ATmega I2C
	bus would never be initialised due to a spelling error in the
	preprocessor checking whether I2C has been configured for building
	or not.

Signed-off-by: Michel Megens <dev@michelmegens.net>
i2c: eeprom: added an I2C eeprom chip driver

Added a driver for the 24C02 I2C EEPROM chip, developed by Atmel. The
driver currently only supports read and write byte operations. A device
interface should be included in the next version.

Signed-off-by: Michel Megens <dev@michelmegens.net>