sandbox: exynos: Move CONFIG_SOUND to Kconfig

Move this over to Kconfig and tidy up.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/sound/Kconfig b/drivers/sound/Kconfig
index e69de29..599edae 100644
--- a/drivers/sound/Kconfig
+++ b/drivers/sound/Kconfig
@@ -0,0 +1,11 @@
+config SOUND
+	bool "Enable sound support"
+	help
+	  Support making sounds through an audio codec. This is normally a
+	  beep at a chosen frequency for a selected length of time. However
+	  the drivers support playing arbitrary sound samples using a
+	  PCM interface.
+
+	  Note: At present the sound setup is somewhat tangled up in that the
+	  audio codecs are called from the sound-i2s code. This could be
+	  converted to driver model.