ASoC: Add WM8728 codec driver

The WM8728 is a high performance stereo DAC designed for applications
such as DVD, home theatre and digital TV.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index b73c36a..8a84460 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -13,6 +13,7 @@
 	select SND_SOC_UDA1380 if I2C
 	select SND_SOC_WM8510 if (I2C || SPI_MASTER)
 	select SND_SOC_WM8580 if I2C
+	select SND_SOC_WM8728 if (I2C || SPI_MASTER)
 	select SND_SOC_WM8731 if (I2C || SPI_MASTER)
 	select SND_SOC_WM8750 if (I2C || SPI_MASTER)
 	select SND_SOC_WM8753 if (I2C || SPI_MASTER)
@@ -93,6 +94,9 @@
 config SND_SOC_WM8580
 	tristate
 
+config SND_SOC_WM8728
+	tristate
+
 config SND_SOC_WM8731
 	tristate