ASoC: Constify struct snd_soc_codec_driver

Allow the CODEC driver structure to be marked const by making all
the APIs that use it do so.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
diff --git a/include/sound/soc.h b/include/sound/soc.h
index 7d53cc4..0eea08e 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -265,7 +265,7 @@
 		struct snd_soc_platform_driver *platform_drv);
 void snd_soc_unregister_platform(struct device *dev);
 int snd_soc_register_codec(struct device *dev,
-		struct snd_soc_codec_driver *codec_drv,
+		const struct snd_soc_codec_driver *codec_drv,
 		struct snd_soc_dai_driver *dai_drv, int num_dai);
 void snd_soc_unregister_codec(struct device *dev);
 int snd_soc_codec_volatile_register(struct snd_soc_codec *codec, int reg);
@@ -453,7 +453,7 @@
 	const char *name_prefix;
 	int id;
 	struct device *dev;
-	struct snd_soc_codec_driver *driver;
+	const struct snd_soc_codec_driver *driver;
 
 	struct mutex mutex;
 	struct snd_soc_card *card;