ARM: dts: vf610: enable USB misc/phy nodes where necessary

Since restructuring of the device tree files, the USB misc/phy
nodes are disabled by default. Hence we need to enable those
explicitly when USB is used.

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