ASoC: wm5110: Add audio CODEC driver

The WM5110 is a highly integrated low power audio subsystem for
smartphones, tablets and other portable audio devices. It combines
an advanced DSP feature set with a flexible, high performance audio
hub CODEC.

This patch adds the audio CODEC driver for the device.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>