ASoC: Remove use of hw_read from TLV320AIC3x driver

The TLV320AIC3x driver is currently the only user of the CODEC hw_read
operation and is jumping through some hoops in order to do so.  In order
to support future refactoring to make the hw_read operation more usable
unwrap the usage in this driver to avoid its use.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>