ASoC: wm2000: Expose ANC gain adjustment

No TLV information since it's not actually a direct gain control.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm2000.c b/sound/soc/codecs/wm2000.c
index 627c454..cb7fa3c 100644
--- a/sound/soc/codecs/wm2000.c
+++ b/sound/soc/codecs/wm2000.c
@@ -650,6 +650,7 @@
 }
 
 static const struct snd_kcontrol_new wm2000_controls[] = {
+	SOC_SINGLE("ANC Volume", WM2000_REG_ANC_GAIN_CTRL, 0, 255, 0),
 	SOC_SINGLE_BOOL_EXT("WM2000 ANC Switch", 0,
 			    wm2000_anc_mode_get,
 			    wm2000_anc_mode_put),
@@ -755,6 +756,8 @@
 {
 	struct wm2000_priv *wm2000 = dev_get_drvdata(codec->dev);
 
+	snd_soc_codec_set_cache_io(codec, 16, 8, SND_SOC_REGMAP);
+
 	/* This will trigger a transition to standby mode by default */
 	wm2000_anc_set_mode(wm2000);