The USB HCD generic binding is used by many USB host bindings.

In order to allow the DT validation to happen on those, let's create a YAML
description for that generic binding that can be referenced later on.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>