Add ISP24xx IOCB manipulation routines.

Add appropriate glue-code for ISP24xx support while
manipulting IOCB packets.  Add an ISP24xx specific
'start_scsi' routine due to command-type-7 layout
changes.
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>