usb: gadget: f_uac1: Add support for UAC1 function

Add support for the UAC1 function with the configfs framework
along with following other changes:
 - Add dynamic updation of AudioStreaming interface numbers in
   the AudioControl interface descriptor.
 - Add superspeed support.
 - Stop playback on func disable so that pending request's
   completion is called before request has been freed in unbind.
 - Fix minor compilation issue.

Change-Id: Ib30fa735314c57b9543f89e18d1fb419ed5a2b9d
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>