ARMV7: OMAP3: Update Beagle xM pinmux with USB hub and DVI gpio setup

This patch adds missing pinmux setup for 4 GPIO signals used on the Beagle xM:
 - USB hub reset (gpio_56)
 - P8 USB hub reset (gpio_63)
 - DVI enable (gpio_129)
 - P8 DVI enable (gpio_170)

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>