scsi: qla2xxx: Use chip reset to bring down laser on unload.

Current code uses Stop Firmware MB cmd to stop the chip before
driver unload.  This will leave the laser in its current state.
This give the illusion of this adapter is still alive.
For 8G & newer adapters, use chip reset to stop the chip and
bring down the laser.

Signed-off-by: Quinn Tran <quinn.tran@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>