arm: dts: Add pinctrl/GPIO/EINT node for mt2701

Add pinctrl and GPIO node to mt2701.dtsi

Signed-off-by: Biao Huang <biao.huang@mediatek.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>