dt-bindings: pinctrl: Add bindings for Actions S500 SoC

Add pinctrl and gpio bindings for Actions Semi S500 SoC.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/7abf618c446b7b648f512afe72e46704156e9912.1596461275.git.cristian.ciocaltea@gmail.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>