set offload_to_be_enabled to 0 when an ioaccel2 error is processed.

Before, an ioaccel completion error would turn of ioaccel but a rescan
would turn it back on again.
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>