gpiolib: add gpiod_to_gpio_device() stub for !GPIOLIB

Add empty stub of gpiod_to_gpio_device() when GPIOLIB is not enabled.

Cc: <stable@vger.kernel.org>
Fixes: 370232d0

 ("gpiolib: provide gpiod_to_gpio_device()")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>