gpiolib: Add missing dummies for the unified device properties interface

If GPIOLIB=n:

    drivers/leds/leds-gpio.c: In function ‘gpio_leds_create’:
    drivers/leds/leds-gpio.c:187: error: implicit declaration of function ‘devm_get_gpiod_from_child’
    drivers/leds/leds-gpio.c:187: warning: assignment makes pointer from integer without a cast

Add dummies for fwnode_get_named_gpiod() and devm_get_gpiod_from_child()
for the !GPIOLIB case to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: 40b73183 ("gpio: Support for unified device properties interface")
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bryan Wu <cooloney@gmail.com>