arm64: dts: mt7622: add EINT support to pinctrl

Add EINT support to pinctrl and set those GPIO keys as interrupt-driven
keys.

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