usb: host: add DT bindings for faraday fotg2

This adds device tree bindings for the Faraday FOTG2
dual-mode host controller.

Cc: devicetree@vger.kernel.org
Signed-off-by: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>