ALSA: ASoC: Convert wm8990 to a new-style i2c driver

Convert the wm8990 codec driver to the new (standard) device driver
binding model. After this change, WM8990 devices are no longer
discovered automatically and must instead be instantiated explicitly.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
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>