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>
diff --git a/sound/soc/codecs/wm8997.c b/sound/soc/codecs/wm8997.c
index 3d50621..09c4150 100644
--- a/sound/soc/codecs/wm8997.c
+++ b/sound/soc/codecs/wm8997.c
@@ -1081,7 +1081,7 @@
 	ARIZONA_DAC_DIGITAL_VOLUME_5R,
 };
 
-struct regmap *wm8997_get_regmap(struct device *dev)
+static struct regmap *wm8997_get_regmap(struct device *dev)
 {
 	struct wm8997_priv *priv = dev_get_drvdata(dev);