cciss: do not use void pointer for scsi hba data

cciss: do not use void pointer for scsi hba data
and get rid of related unnecessary type casting
and delete some superfluous and misleading comments nearby.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>