ASoC: da732x: Use da732x->regmap instead of codec->control_data

With the ongoing component-ization of the ASoC framework and the continuing
migration to using regmap for IO the control_data field of the snd_soc_codec
struct will eventually be removed. Prepare the da732x driver for this by using
da732x->regmap instead of accessing the CODEC's control_data field.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@linaro.org>