ASoC: MAX9877: add MAX9877 amp driver

The MAX9877 combines a high-efficiency Class D audio power amplifier
with a stereo Class AB capacitor-less DirectDrive headphone amplifier.

The max9877_add_controls() is called to register the MAX9877 specific
controls on machine specific init() of the machine driver.

The datasheet for the MAX9877 can find at the following url:
http://datasheets.maxim-ic.com/en/ds/MAX9877.pdf

[Slight edit to sort the ALL_CODECS entries -- broonie.]

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index b674d3a..4219a41 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -17,6 +17,7 @@
 	select SND_SOC_AK4104 if SPI_MASTER
 	select SND_SOC_AK4535 if I2C
 	select SND_SOC_CS4270 if I2C
+	select SND_SOC_MAX9877 if I2C
 	select SND_SOC_PCM3008
 	select SND_SOC_SPDIF
 	select SND_SOC_SSM2602 if I2C
@@ -188,3 +189,7 @@
 
 config SND_SOC_WM9713
 	tristate
+
+# Amp
+config SND_SOC_MAX9877
+	tristate