i2c: ST DDC I2C U300 bus driver v3

This adds support for the ST Microelectronics DDC I2C bus
driver. This bus is used in the U300 architecture recently
added to RMK:s ARM tree.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Reviewed-by: Ben Dooks <ben-linux@fluff.org>
Reviewed-by: Jean Delvare <khali@linus-fr.org>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>