ramips: dts: add the missing interrupt properties for GPIO nodes

ramips: dts: add the missing interrupt properties for GPIO nodes

The Ralink GPIO driver supports irqchip function. Hence we need to
add "interrupt-parent" and "interrupt-controller" properties to make
sure it works properly. It is worth noting that all GPIO devices
share the same interrupt line.

Signed-off-by: Shiji Yang <yangshiji66@qq.com>
Link: https://github.com/openwrt/openwrt/pull/16764
Signed-off-by: Robert Marko <robimarko@gmail.com>