pinctrl: don't include GPIOLIB private header

gpio_to_desc() is declared in linux/gpio.h so there's no need to include
gpiolib.h directly.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20231115165001.2932350-4-brgl@bgdev.pl


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>