[SCSI] aic7xxx: fix boot hang with Fujitsu drives

Apparently these are the only drives that try to negotiate IU and QAS
at u160 speeds.  The aic7xxx driver can't cope with this.  The fix is
to eliminate the IU and QAS setting routines.  I've #if 0'd them out,
just in case we ever get the sequencer documentation out of Adaptec,
since we'd then be able to fix the driver.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>