[SCSI] aacraid: Fix aacraid probe breakage (updated)

This patch fixes the bad assumption of the aacraid driver with use_sg.
I used the 3w-xxxx driver fix as a guide for this.

Signed-off-by: Mark Haverkamp <markh@osdl.org>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>