[ALSA] snd-aoa: not experimental

The dependencies in the soundbus Kconfig were wrong, it isn't
experimental any more.
This patch fixes that and makes it select SND_PCM too instead of
depending on it.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/aoa/soundbus/Kconfig

 config SND_AOA_SOUNDBUS
 	tristate "Apple Soundbus support"
-	depends on SOUND && SND_PCM && EXPERIMENTAL
+	depends on SOUND
+	select SND_PCM
 	---help---
 	This option enables the generic driver for the soundbus
 	support on Apple machines.