Audio: modify audio driver satisfy alsa dmix

Signed-off-by: yangyalei <[email protected]>

Author: yangyalei

audio/Kconfig

@@ -277,4 +277,10 @@ config AUDIO_FONT
 
 endif
 
+config AUDIO_MAX_APPS
+	int "Number of applications that can use upperhalf driver meanwhile"
+	default 3
+	---help---
+		Specifies the number of applications can play audio data meanwhile.
+
 endif