This patch prepares for the removal of the request pointer from struct
scsi_cmnd and does not change any functionality.

Link: https://lore.kernel.org/r/20210809230355.8186-13-bvanassche@acm.org
Cc: Michael Schmitz <schmitzmic@gmail.com>
Suggested-by: Finn Thain <fthain@linux-m68k.org>
Acked-by: Finn Thain <fthain@linux-m68k.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>