PCI: Add DT bindings for Faraday Technology PCI Host Bridge

Add device tree bindings for the Faraday technology PCI Host Bridge.  This
IP is found in the Storlink/Storm/Cortina Gemini SoC platform.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>
CC: Janos Laube <janos.dev@gmail.com>
CC: Paulius Zaleckas <paulius.zaleckas@gmail.com>
CC: Hans Ulli Kroll <ulli.kroll@googlemail.com>
CC: Florian Fainelli <f.fainelli@gmail.com>
CC: devicetree@vger.kernel.org
CC: Feng-Hsin Chiang <john453@faraday-tech.com>
CC: Greentime Hu <green.hu@gmail.com>