I'm working on adding a board to Zephyr. I'm attempting to use a board.c file to configure GPIO pins as output and initialize them low on start-up. I've attempted to follow existing boards, but am not being successful. device_get_binding() always returns NULL so the call to gpio_pin_configure() never occurs. I took the nrf52840dk_nrf52840 board and added CMakeLists.txt and board.c.