Move hosted codec header files back under firmware/export

This is a partial revert of a79bdaf46

It caused all sorts of build breakages for misc stuff like the dbtool,
which doesn't include any per-target build directories

Change-Id: I493a33c1859706679972e47c96196223415985d9

firmware/export/nwzlinux_codec.h

@@ -0,0 +1,45 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ *
+ * Copyright (C) 2016 by Amaury Pouly
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#ifndef __NWZLINUX_CODEC_H__
+#define __NWZLINUX_CODEC_H__
+
+#define AUDIOHW_CAPS 0
+
+/* Ranges from -100dB to 4dB */
+AUDIOHW_SETTING(VOLUME,       "dB", 0,  1, -100,  4, -10)
+
+enum nwz_src_t
+{
+    NWZ_PLAYBACK,
+    NWZ_RADIO,
+    NWZ_MIC,
+};
+
+/* enable/disable Sony's "acoustic" mode */
+bool audiohw_acoustic_enabled(void);
+void audiohw_enable_acoustic(bool en);
+/* enable/disable Sony's "cuerev" mode */
+bool audiohw_cuerev_enabled(void);
+void audiohw_enable_cuerev(bool en);
+/* select playback source */
+void audiohw_set_playback_src(enum nwz_src_t src);
+
+#endif /* __NWZLINUX_CODEC_H__ */