ASoC: adau1373: Use SOC_ENUM_SINGLE_VIRT_DECL()

For the upcoming consolidation for MUXs and virtual MUXs we need to mark virtual
enums as such.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/codecs/adau1373.c

@@ -576,8 +576,8 @@ static const char *adau1373_decimator_text[] = {
 	"DMIC1",
 };
 
-static SOC_ENUM_SINGLE_DECL(adau1373_decimator_enum,
-			    0, 0, adau1373_decimator_text);
+static SOC_ENUM_SINGLE_VIRT_DECL(adau1373_decimator_enum,
+	adau1373_decimator_text);
 
 static const struct snd_kcontrol_new adau1373_decimator_mux =
 	SOC_DAPM_ENUM_VIRT("Decimator Mux", adau1373_decimator_enum);