ASoC: max9768: add driver for max9768 amplifier

Add a driver supporting the volume control and the mute pin. Shdn pin
and DAPM are not taken care of yet.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
4 files changed