scsi: sym53c500_cs: Stop using struct scsi_pointer

This driver doesn't use SCp.ptr to save a SCSI command data pointer which
means "scsi pointer" is a complete misnomer here. Only a few members of
struct scsi_pointer are needed so move those to private command data.

Link: https://lore.kernel.org/r/accf71e293ba3aed6d18c8baeb405de8dfe7c935.1649235939.git.fthain@linux-m68k.org


Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>