driver: gpio: it8xxx2: enable gpio_driver_config
driver: gpio: it8xxx2: enable gpio_driver_config

Fix assertion of unsupported pin.

This change also remove ngpios field.

Signed-off-by: Dino Li <338d523ecf3700bd86eb9c34d220f91911d2a18c@ite.com.tw>

finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr