[SCSI] aic79xx: Remove busyq

From: Jeff Garzik <jgarzik@pobox.com>

This patch removes the busyq in aic79xx and uses the command-queue from 
the midlayer instead. Additionally some dead code is removed.

Signed-off-by: Hannes Reinecke <hare@suse.de>

Fixed rejections

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