pinctrl: dt-bindings: Add documentation for Armada 37xx pin controllers

Document the device tree binding for the pin controllers found on the
Armada 37xx SoCs.

Update the binding documention of the xtal clk which is a subnode of this
syscon node.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
[Fixed gpios node]
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

dt-bindings: clock: add DT binding for the Xtal clock on Armada 3700

This commit adds the DT binding documentation for the the Xtal clock on
Armada 3700 used in the Marvell Armada 3700 SoCs.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>