arm64: dts: mt7622: use gpio-ranges to pinctrl device

Using gpio-ranges property represent which GPIOs correspond to which pins
on MT7622 pin controllers. For details, we can see section 2.1 of
Documentation/devicetree/bindings/gpio/gpio.txt to know how to bind pinctrl
and gpio drivers via the "gpio-ranges" property.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>