spi: s3c64xx: Drop custom gpio setup argument

spi: s3c64xx: Drop custom gpio setup argument

The SPI0 platform population function was taking a custom
gpio setup callback but the only user pass NULL as
argument so drop this argument.

Cc: linux-samsung-soc@vger.kernel.org
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Sylwester Nawrocki <snawrocki@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20220118230915.157797-2-linus.walleij@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>