ASoC: da732x: Replace hw_read usage with snd_soc_read()

Pre-merge code was using direct hw_read() calls as an out of framework
way of doing volatile register I/O when not using regmap. This has never
functioned correctly in mainline due to the regmap conversion, the
hw_read() implementation still does caching. In order to facilitate
removal of the subsystem level I/O code convert to use snd_soc_read(),
there should be no functional impact.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>