The struct sdw_port_config is not modified, so make it a const for code
safety.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230124163953.345949-2-krzysztof.kozlowski@linaro.org


Signed-off-by: Mark Brown <broonie@kernel.org>