Refactor aio submission code:

    1. Break up function pqi_raid_bypass_submit_scsi_cmd()
       into smaller functions.

    2. Add common block (rmd - raid_map_data) to carry around into newly
       added functions.

    3. Prepare for new AIO functionality.

No functional changes.

Link: https://lore.kernel.org/r/161549371553.25025.8840958689316611074.stgit@brunhildaReviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>