8K quirks & making quirk table more structured

[Will Andrews]

Hi,

We have seen 8K blocksize devices in our lab, which require quirks to
behave properly.  Rather than simply add another quirk for a different
size, we made the quirk entries more structured, and changed blocksize
to be a fixed-size integer element.

Please review: http://people.freebsd.org/~will/head-convert-cam-quirk-tables-to-structs.diff

The naming isn't particularly intuitive, but I'd like to check this in
as primarily a structural change, and follow up with other
improvements later.

Thanks!
--Will.