ASoC: tlv320aic23: add support for SPI control mode

tlv320aic23 chip control interface may work in either I2C or SPI mode
depending on the MODE pin state. Functionality and register layout are
independent of the control mode.

Implement bus-specific parts as separate modules.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>