dts: bindings: gpio: nrf-gpiote: Extend description

Add new feature flags to gpiote node.
Include pinctrl. Pins used by GPIOTE0 on nrf54h20/cpurad require CTRLSEL
configuration. Pins are listed using pinctrl and parsed by nrf-regtool
to prepare UICR configuration.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>