mx5: Add USB device definitions for Freescale MX51 Babbage HW

This patch is part of enabling USB for Freescale MX51 Babbage HW. This
patch adds device structures for USB Host1 and OTG port, and adds
clocking information for USB HW.

This patch applies to 2.6.34-rc6.

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