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

sound/soc/codecs/rt5682-sdw.c

@@ -160,7 +160,7 @@ static int rt5682_read_prop(struct sdw_slave *slave)
 #define RT5682_CLK_FREQ_2400000HZ 2400000
 #define RT5682_CLK_FREQ_12288000HZ 12288000
 
-int rt5682_clock_config(struct device *dev)
+static int rt5682_clock_config(struct device *dev)
 {
 	struct rt5682_priv *rt5682 = dev_get_drvdata(dev);
 	unsigned int clk_freq, value;