ASoC: rt5514: fix gcc-7 warning

gcc-7 warns that there is a duplicate 'const' specifier in some
variables that are declared using the SOC_ENUM_SINGLE_DECL macro:

sound/soc/codecs/rt5514.c:398:14: error: duplicate 'const' declaration specifier [-Werror=duplicate-decl-specifier]
 static const SOC_ENUM_SINGLE_DECL(
sound/soc/codecs/rt5514.c:405:14: error: duplicate 'const' declaration specifier [-Werror=duplicate-decl-specifier]
 static const SOC_ENUM_SINGLE_DECL(

This removes one to fix the warning.

Fixes: 4a6180ea7399 ("ASoC: rt5514: add rt5514 codec driver")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/rt5514.c

@@ -395,14 +395,14 @@ static const char * const rt5514_dmic_src[] = {
 	"DMIC1", "DMIC2"
 };
 
-static const SOC_ENUM_SINGLE_DECL(
+static SOC_ENUM_SINGLE_DECL(
 	rt5514_stereo1_dmic_enum, RT5514_DIG_SOURCE_CTRL,
 	RT5514_AD0_DMIC_INPUT_SEL_SFT, rt5514_dmic_src);
 
 static const struct snd_kcontrol_new rt5514_sto1_dmic_mux =
 	SOC_DAPM_ENUM("Stereo1 DMIC Source", rt5514_stereo1_dmic_enum);
 
-static const SOC_ENUM_SINGLE_DECL(
+static SOC_ENUM_SINGLE_DECL(
 	rt5514_stereo2_dmic_enum, RT5514_DIG_SOURCE_CTRL,
 	RT5514_AD1_DMIC_INPUT_SEL_SFT, rt5514_dmic_src);