MFC r242127, r240078, r240609, r241988, r242129, r242223, r242438,
r242453, r242455 and r242458:
Add full support for Fast Track Ultra 8R from M-audio.
Implement support for USB Audio v2.0.
Remove some redundant USB audio v1.0 debug data. Use lsusb instead.
Implement support for the so-called USB feedback endpoint for USB
audio devices.
Export all mixer nodes into dev.pcm.X.mixer.Y sysctl nodes.
PR: usb/171254
git-svn-id: svn://svn.freebsd.org/base/stable/9@242822
ccf9f872-aa2e-dd11-9fc8-
001c23d0bc1f