ASoC: rt5682: Make rt5682_clock_config static

Fix sparse warning:

sound/soc/codecs/rt5682-sdw.c:163:5: warning:
 symbol 'rt5682_clock_config' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200228075609.38236-1-yuehaibing@huawei.com


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