[ALSA] ASoC codecs: WM9712 support

This patch adds ASoC support for the WM9712 codec.
Supported features:-
o Capture/Playback/Sidetone/Bypass.
o Aux DAC.
o 8k - 48k sample rates.
o DAPM.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>