ALSA: ASoC: Add custom SOC_SINGLE_TLV for tlv320aic23 codec

Replaces SOC_ENUM with custom SOC_SINGLE_TLV for Sidetone volume

Signed-off-by: Arun KS <arunks@mistralsolutions.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>