aha1542: Pass struct Scsi_Host * to functions

Pass struct Scsi_Host * to functions instead of base address.
This reduces the number of parameters and is also required for printk
conversion.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>