scsi: smartpqi: Update attribute name to `driver_version`

The file name in the documentation is currently incorrect, so fix it.

Link: https://lore.kernel.org/r/fe264d62-0371-ea59-b66a-6d855290ce65@molgen.mpg.de


Fixes: 6d90615f ("scsi: smartpqi: add sysfs entries")
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>