ASoC: codecs: src4xxx-i2c: Mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  sound/soc/codecs/src4xxx-i2c.c:27:34: error: ‘src4xxx_of_match’ defined but not used [-Werror=unused-const-variable=]

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230310214333.274903-9-krzysztof.kozlowski@linaro.org


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