mxc: Update GPIO for USB support on Freescale MX51 Babbage HW

This patch is part of enabling USB for Freescale MX51 Babbage HW. This
patch updates the iomux pins for USB, and gpio line for reset the
USB hub on the MX51 Babbage 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>