dts: mcxn947: Fix input key error

Fix the compile error when input driver is enabled.
Error message:
In file included from zephyr/zephyr/include/zephyr/sys/util_macro.h:34,
                 from zephyr/zephyr/include/zephyr/irq_multilevel.h:15,
                 from zephyr/zephyr/include/zephyr/devicetree.h:20,
                 from zephyr/zephyr/include/zephyr/device.h:12,
                 from zephyr/zephyr/drivers/input/input_gpio_keys.c:9:
zephyr/zephyr/include/zephyr/toolchain/gcc.h:87:36:
error: static assertion failed:
"zephyr-code must be specified to use the input-gpio-keys driver"

Signed-off-by: Jason Yu <zejiang.yu@nxp.com>