scsi: hpsa: remove coalescing settings for ioaccel2

- Setting coalescing has a significant negative impact on low
  queue-depth performance.
- Does not help high queue-depth performance.

Signed-off-by: Don Brace <don.brace@microsemi.com>
Reviewed-by: Scott Benesh <scott.benesh@microsemi.com>
Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microsemi.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>