compulab: eeprom: add support for defining eeprom i2c bus

Create CONFIG_SYS_I2C_EEPROM_BUS #define to tell the EEPROM
module what I2C bus the EEPROM is located at. Make cl_eeprom_read()
switch to that bus when reading EEPROM.

Cc: Igor Grinberg <grinberg@compulab.co.il>
Cc: Dmitry Lifshitz <lifshitz@compulab.co.il>
Cc: Tom Rini <trini@ti.com>
Cc: Marek Vasut <marex@denx.de>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Dmitry Lifshitz <lifshitz@compulab.co.il>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>