[ALSA] ASoC codecs: build files

This patch adds an ASoC Makefile and Kconfig for the WM8731, WM8750 and
WM9712 codecs.

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>
diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
new file mode 100644
index 0000000..78ac268
--- /dev/null
+++ b/sound/soc/codecs/Kconfig
@@ -0,0 +1,15 @@
+config SND_SOC_AC97_CODEC
+	tristate
+	depends SND_SOC
+
+config SND_SOC_WM8731
+	tristate
+	depends SND_SOC
+
+config SND_SOC_WM8750
+	tristate
+	depends SND_SOC
+
+config SND_SOC_WM9712
+	tristate
+	depends SND_SOC