Our pin controller can configure the pins no matter how they are muxed, so
it makes sense to allow this for GPIOs as well.

Add the generic set_config function so that we can rely on the existing
pinctrl code we have.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>