sound: ASoC: Fix dependency on AC97_BUS

When built with AC97 support the ASoC core depends on AC97_BUS so force
it to be available Kconfig.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/soc/Kconfig

@@ -5,6 +5,7 @@
 menuconfig SND_SOC
 	tristate "ALSA for SoC audio support"
 	select SND_PCM
+	select AC97_BUS if SND_SOC_AC97_BUS
 	---help---
 
 	  If you want ASoC support, you should say Y here and also to the