[DeviceDrivers] Add audio.h header file.

components/drivers/include/drivers/audio.h

+#ifndef AUDIO_H__
+#define AUDIO_H__
+
+/* Device Control Commands */
+#define CODEC_CMD_RESET             0
+#define CODEC_CMD_SET_VOLUME        1
+#define CODEC_CMD_GET_VOLUME        2
+#define CODEC_CMD_SAMPLERATE        3
+#define CODEC_CMD_EQ                4
+#define CODEC_CMD_3D                5
+
+#define CODEC_VOLUME_MAX            (63)
+
+#endif