ASoC: si476x: Fix IO setup

The si476x is a MFD device and the CODEC driver is using the regmap struct of
the parent device, hence automatic IO setup will not work and we need to
manually call snd_soc_codec_set_cache_io(). The issue was introduced commit
d6173df35f ("ASoC: si476x: Remove custom register I/O implementation")

Fixes: d6173df35f ("ASoC: si476x: Remove custom register I/O implementation")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
Cc: stable@vger.kernel.org

sound/soc/codecs/si476x.c

@@ -210,7 +210,7 @@ out:
 static int si476x_codec_probe(struct snd_soc_codec *codec)
 {
 	codec->control_data = dev_get_regmap(codec->dev->parent, NULL);
-	return 0;
+	return snd_soc_codec_set_cache_io(codec, 0, 0, SND_SOC_REGMAP);
 }
 
 static struct snd_soc_dai_ops si476x_dai_ops = {