HD audio widget naming

["Jared D. McNeill" <jmcneill%invisible.ca@localhost>]

Actually, now that I think of it, I did try to give some sense to 
auto-generated mixer controls[1], it works well enough at least on my 
Eee PC, but I haven't enabled it for any other codecs.

Cheers,
Jared

[1] http://nxr.netbsd.org/source/xref/sys/dev/pci/azalia_codec.c#1243