ASoC: wm8990: Use supplies to manage input power

Instead of using a fake register use a supply widget to manage the power
for the inputs, this is more idiomatic and supports regmap conversion.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>

diff --cc sound/soc/codecs/wm8990.c
Simple merge

diff --cc sound/soc/codecs/wm8990.h
Simple merge