Add RAID1 write IU and implement RAID1 write support. Change brand names
ADM/ADG to TRIPLE/RAID-6.

Link: https://lore.kernel.org/r/161549373324.25025.2441592111049564780.stgit@brunhildaReviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>