All struct s3c64xx_spi_port_config should be const.

Fixes: 4ebb15a1 ("spi: s3c64xx: Add spi port configuration for Tesla FSD SoC")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220627094541.95166-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>