added Documentation/scsi/smartpqi.txt

[mkp: applied by hand]
Reviewed-by: Kevin Barnett <kevin.barnett@microsemi.com>
Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>