ASoC: sta32x: Fix cache sync

ASoC: sta32x: Fix cache sync

commit 70ff00f82a6af0ff68f8f7b411738634ce2f20d0 upstream.

codec->control_data contains a pointer to the regmap struct of the device, not
to the device private data. Use snd_soc_codec_get_drvdata() instead.

The issue was introduced in commit 29fdf4fbbe ("ASoC: sta32x: Convert to
regmap").

Fixes: 29fdf4fbbe (ASoC: sta32x: Convert to regmap)
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>