mps(4) via 8-STABLE (6Gb HBA suppport)

Since we have an updated mfi(4) from 8-STABLE, it may be meaningful
to also suck in the updates to the HBA only models from LSI.
(some HBA/RAID cards are cross-flashable between operational modes)

While this doesn't explicitely add new hardware support, it fixes
memory leaks and other bugs they one may not want to see in production.

This wraps all changes into one large patch from cherry picks via
8-STABLE applied on a clean 8.3-RELENG branch.

See the readme to get an idea what is included (hopefully helpful for later merges)