usb: gadget: f_uac2: convert to new function interface with backward compatibility

Converting uac2 to the new function interface requires converting
the USB uac2's function code and its users.

This patch converts the f_uac2.c to the new function interface.

The file is now compiled into a separate usb_f_uac2.ko module.

The old function interface is provided by means of a preprocessor
conditional directives. After all users are converted, the old interface
can be removed.

Tested-by: Sebastian Reimers <sebastian.reimers@googlemail.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/function/u_uac2.h

@@ -0,0 +1,32 @@
+/*
+ * u_uac2.h
+ *
+ * Utility definitions for UAC2 function
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ *		http://www.samsung.com
+ *
+ * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef U_UAC2_H
+#define U_UAC2_H
+
+#include <linux/usb/composite.h>
+
+struct f_uac2_opts {
+	struct usb_function_instance	func_inst;
+	int				p_chmask;
+	int				p_srate;
+	int				p_ssize;
+	int				c_chmask;
+	int				c_srate;
+	int				c_ssize;
+	bool				bound;
+};
+
+#endif