ASoC: Add const to SOC_ENUM_*_DECL() macros

Since these macros are supposed to be used for decalring const
objects, let's add the const modifier there.

The doubled const appearing in usages will be cleaned by later
patches.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/sound/soc.h

@@ -272,14 +272,14 @@
  * ARRAY_SIZE internally
  */
 #define SOC_ENUM_DOUBLE_DECL(name, xreg, xshift_l, xshift_r, xtexts) \
-	struct soc_enum name = SOC_ENUM_DOUBLE(xreg, xshift_l, xshift_r, \
+	const struct soc_enum name = SOC_ENUM_DOUBLE(xreg, xshift_l, xshift_r, \
 						ARRAY_SIZE(xtexts), xtexts)
 #define SOC_ENUM_SINGLE_DECL(name, xreg, xshift, xtexts) \
 	SOC_ENUM_DOUBLE_DECL(name, xreg, xshift, xshift, xtexts)
 #define SOC_ENUM_SINGLE_EXT_DECL(name, xtexts) \
-	struct soc_enum name = SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(xtexts), xtexts)
+	const struct soc_enum name = SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(xtexts), xtexts)
 #define SOC_VALUE_ENUM_DOUBLE_DECL(name, xreg, xshift_l, xshift_r, xmask, xtexts, xvalues) \
-	struct soc_enum name = SOC_VALUE_ENUM_DOUBLE(xreg, xshift_l, xshift_r, xmask, \
+	const struct soc_enum name = SOC_VALUE_ENUM_DOUBLE(xreg, xshift_l, xshift_r, xmask, \
 							ARRAY_SIZE(xtexts), xtexts, xvalues)
 #define SOC_VALUE_ENUM_SINGLE_DECL(name, xreg, xshift, xmask, xtexts, xvalues) \
 	SOC_VALUE_ENUM_DOUBLE_DECL(name, xreg, xshift, xshift, xmask, xtexts, xvalues)