scsi: dmx3191d: use module_pci_driver

Use module_pci_driver() helper to simplify the code.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Acked-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>