libata: blacklist Seagate drives which time out FLUSH_CACHE when used with NCQ

Some recent Seagate harddrives have firmware bug which causes FLUSH
CACHE to timeout under certain circumstances if NCQ is being used.
This can be worked around by disabling NCQ and fixed by updating the
firmware.  Implement ATA_HORKAGE_FIRMWARE_UPDATE and blacklist these
devices.

The wiki page has been updated to contain information on this issue.

  http://ata.wiki.kernel.org/index.php/Known_issues



Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>