ASoC: codec: fix the sparse check warnings.

Some thing Likes:

reproduce: make C=1 CF=-D__CHECK_ENDIAN__

sparse warnings: (new ones prefixed by >>)

>> sound/soc/codecs/wm8997.c:1084:15: sparse: symbol \
'wm8997_get_regmap' was not declared. Should it be static?

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/codecs/si476x.c

@@ -231,7 +231,7 @@ static struct snd_soc_dai_driver si476x_dai = {
 	.ops		= &si476x_dai_ops,
 };
 
-struct regmap *si476x_get_regmap(struct device *dev)
+static struct regmap *si476x_get_regmap(struct device *dev)
 {
 	return dev_get_regmap(dev->parent, NULL);
 }