mx5: Register i2c on Freescale MX51 Babbage HW

Add device registration and setup IOMUX pins in the mx51_babbage
board feil.

Signed-off-by: Dinh Nguyen <Dinh.Nguyen@freescale.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>