ASoC: ams-delta: remove duplicate 'const'

clang points out that SOC_ENUM_SINGLE_EXT_DECL() contains a 'const'
modifier already, so adding another one does not make it more const:

sound/soc/ti/ams-delta.c:203:14: error: duplicate 'const' declaration specifier [-Werror,-Wduplicate-decl-specifier]
static const SOC_ENUM_SINGLE_EXT_DECL(ams_delta_audio_enum,
             ^
include/sound/soc.h:351:2: note: expanded from macro 'SOC_ENUM_SINGLE_EXT_DECL'
        const struct soc_enum name = SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(xtexts), xtexts)
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/ti/ams-delta.c

@@ -200,7 +200,7 @@ static int ams_delta_get_audio_mode(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static const SOC_ENUM_SINGLE_EXT_DECL(ams_delta_audio_enum,
+static SOC_ENUM_SINGLE_EXT_DECL(ams_delta_audio_enum,
 				      ams_delta_audio_mode);
 
 static const struct snd_kcontrol_new ams_delta_audio_controls[] = {