scsi: dc395x: Drop internal SCSI message definitions

Drop the internal SCSI message definitions and use the functions provided
by the SPI transport class.

Link: https://lore.kernel.org/r/20210113090500.129644-21-hare@suse.de


Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>