leds: gpio: set led_dat->gpiod pointer for OF defined GPIO leds

Commit 45d4c6de ("leds: gpio: Try to lookup gpiod from device")
removed the common code path that set the led_dat->gpiod pointer in
create_gpio_led(), but only added it back for the devices that have
a valid gpio_led_platform_data structure. Calling gpio_leds_create()
in gpio_led_probe() is not enough to get a valid gpiod pointer.

Fortunately enough, gpio_leds_create() already gets the needed pointer,
we just need to assign it to the relevant gpio_led_data structure.

Fixes: 45d4c6de

 ("leds: gpio: Try to lookup gpiod from device")
Signed-off-by: Liviu Dudau <liviu@dudau.co.uk>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>