Support for sos@

[Nate Lawson]

Based on some private emails I received, I'd like to clarify my comments
on the previous SATA commit.  I appreciate sos@ and the fact that he has
been working on ata, syscons, etc. for quite a long time.  As someone who
is also affected by undocumented hardware that doesn't quite conform to
the spec, I know things can be frustrating.  I also hope that to the
extent possible, we continue to improve FreeBSD and its documentation.

Thanks,
-Nate