ARM: dts: vf610-twr: Add USB support

Add USB support for Freescale Vybrid tower. The USB hosts over-current
protection signal is not connected to the PHY's over- current
protection, hence we need to disable it.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>