dt-bindings: pinctrl: add binding for Ralink RT305X pinctrl

Add binding for the Ralink RT305X pin controller for RT3050, RT3052,
RT3350, RT3352 and RT5350 SoCs.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20220414173916.5552-14-arinc.unal@arinc9.com


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