aha1524: Use struct scsi_cmnd

Use struct scsi_cmnd instead of Scsi_Cmnd and also rename the variables
to get rid of SC prefix
Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>