ASoC: add a WM8978 codec driver

The WM8978 codec from Wolfson Microelectronics is very similar to
wm8974, but is stereo and also has some differences in pin configuration
and internal signal routing. This driver is based on wm8974 and takes
the differences into account.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index 62ff26a..0aad72f 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -57,6 +57,7 @@
 	select SND_SOC_WM8961 if I2C
 	select SND_SOC_WM8971 if I2C
 	select SND_SOC_WM8974 if I2C
+	select SND_SOC_WM8978 if I2C
 	select SND_SOC_WM8988 if SND_SOC_I2C_AND_SPI
 	select SND_SOC_WM8990 if I2C
 	select SND_SOC_WM8993 if I2C
@@ -230,6 +231,9 @@
 config SND_SOC_WM8974
 	tristate
 
+config SND_SOC_WM8978
+	tristate
+
 config SND_SOC_WM8988
 	tristate