Add a quirk entry for the Seagate Medalist Pro 6 gig drive.  It seems this drive has very poor write performance (1.4MB/sec vs. 12MB/sec) with anything more than two oustanding transactions.
Add a quirk entry for the Seagate Medalist Pro 6 gig drive.  It seems this
drive has very poor write performance (1.4MB/sec vs. 12MB/sec) with anything
more than two oustanding transactions.

So, this limits the number of tagged commands to two for that drive.
Thanks to Paul van der Zwan for doing a whole lot of testing to confirm
this.

Reported by:	Paul van der Zwan <paulz@trantor.xs4all.nl>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase