dt-bindings: pinctrl: convert rockchip,pinctrl.txt to YAML

Convert rockchip,pinctrl.txt to YAML

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Link: https://lore.kernel.org/r/20211007144019.7461-1-jbx6244@gmail.com


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