ALSA: ASoC: Add WM8900 CODEC driver

The WM8900 is designed for portable multimedia applications requiring
low power consumption, high performance audio and a compact form factor
providing:

 - 24 bit stereo ADC and DAC
 - Microphone and line inputs
 - Line outputs
 - Class G headphone amplifier

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>