gpio: replace trivial implementations of request/free with generic one

Replace all trivial request/free callbacks that do nothing but call into
pinctrl code with the generic versions.

Signed-off-by: Jonas Gorski <jogo@openwrt.org>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Stefan Agner <stefan@agner.ch>
Acked-by: Joachim Eastwood <manabian@gmail.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>