ASoC: tas571x: New driver for TI TAS571x power amplifiers

Introduce a new codec driver for the Texas Instruments
TAS5711/TAS5717/TAS5719 power amplifier chips.  These chips are typically
used to take an I2S digital audio input and drive 10-20W into a pair of
speakers.

Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>