ASoC: samsung: Remove obsoleted declaration for s3c64xx_ac97_setup_gpio

The s3c64xx_ac97_setup_gpio() have been removed since
commit 0d297df0 ("ARM: s3c: simplify platform code"), and now
it is useless, so remove it.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20240826033118.4021727-1-cuigaosheng1@huawei.com


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>