Support the TI TAS2552 Class D amplifier.

The TAS2552 is a high efficiency Class-D audio
power amplifier with advanced battery current
management and an integrated Class-G boost
The device constantly measures the
current and voltage across the load and provides a
digital stream of this information.
Signed-off-by: NDan Murphy <dmurphy@ti.com>
Signed-off-by: NMark Brown <broonie@linaro.org>