ARM: dts: imx23-evk: enable USB PHY and controller

The i.MX23EVK board provides a USB port so the USB PHY and controller
need to be enabled for it to be usable.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>