gpio: drop devm_gpio_chip_match()

Commit 48207d75 ("gpio: drop devm_gpiochip_remove()") dropped the
last user of drop devm_gpio_chip_match(), causing a defined but not used
compilation warning. Fix it by removing the function.

Fixes: 48207d75 ("gpio: drop devm_gpiochip_remove()")
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>