ASoC: tlv320aic31xx: remove unused variable 'cm_m_enum'

sound/soc/codecs/tlv320aic31xx.c:261:29: warning:
 cm_m_enum defined but not used [-Wunused-const-variable=]

It is never used, so can be removed.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190815091738.21680-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/tlv320aic31xx.c

@@ -258,7 +258,6 @@ static SOC_ENUM_SINGLE_DECL(mic1rp_p_enum, AIC31XX_MICPGAPI, 4,
 static SOC_ENUM_SINGLE_DECL(mic1lm_p_enum, AIC31XX_MICPGAPI, 2,
 	mic_select_text);
 
-static SOC_ENUM_SINGLE_DECL(cm_m_enum, AIC31XX_MICPGAMI, 6, mic_select_text);
 static SOC_ENUM_SINGLE_DECL(mic1lm_m_enum, AIC31XX_MICPGAMI, 4,
 	mic_select_text);