[SCSI] aic7xxx: clean up eisa support

 - the eisa layer only probes when it's actually safe, no need for
   a driver option
 - store the id table directly in linux format instead of convering
   at runtime

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>