add audio controls from consumer page(HID)

usb_extra.h

@@ -0,0 +1,20 @@
+#ifndef USB_EXTRA_H
+#define  USB_EXTRA_H 1
+
+#include <stdint.h>
+#include "usb.h"
+
+
+#define EXTRA_INTERFACE		3
+#define EXTRA_ENDPOINT		4
+#define EXTRA_SIZE		2
+#define EXTRA_BUFFER		EP_DOUBLE_BUFFER
+
+#define AUDIO_VOL_UP		(1<<0)
+#define AUDIO_VOL_DOWN		(1<<1)
+#define AUDIO_MUTE		(1<<2)
+
+
+int8_t usb_extra_send(uint8_t bits);
+
+#endif