The driver was calling scsi_scan_host before enabling interrupts.

This has gone unnoticed except for customers running in intx mode.
Calling scsi_scan_host before interrupts are enabled causes
"irq XX: nobody cared" messages and the driver to hang.

This patch enables interrupts before the call to scsi_scan_host.
Reported-by: NPiotr Karbowski <piotr.karbowski@gmail.com>
Reviewed-by: NScott Teel <scott.teel@microsemi.com>
Reviewed-by: NKevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: NDon Brace <don.brace@microsemi.com>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>