gpio: Drop superfluous dependencies on GPIOLIB

All config options for GPIO drivers are inside a big "if GPIOLIB ...
endif" block, so there is no reason for individual config options to
have expicit dependencies on GPIOLIB.  Hence remove them.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>