Convert mac_scsi to platform device and eliminate scsi_register().

Platform resources for chip registers now follow the documentation. This
should fix issues with the Mac IIci (and possibly other models too).
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NChristoph Hellwig <hch@lst.de>