fdt: add basic usb nodes support.

The Odriod-C1 has an internal USB node with a reset GPIO. The USB node
support here detects the usb node (in this case a device) and {,de-}asserts
the GPIO pin.

The Linux device tree specification for this is less than ideal.

Done correctly with the "fdt" interface attribute on the dwctwo_fdt
attachment now that this is supported in the config(5) system.

With a big thankyou to Jason.

Revert previous

fdt: add basic usb nodes support.

The Odriod-C1 has an internal USB node with a reset GPIO. The USB node
support here detects the usb node (in this case a device) and {,de-}asserts
the GPIO pin.

The Linux device tree specification for this is less than ideal.

To quote Jason

The "fdt" interface attribute should really go on the dwctwo_fdt
attachment, but that doesn't work in the config(5) system; interface
attributes can only go onto devices.