[SCSI] aic79xx: target hotplug fixes

When a target is added aic79xx tries to be overly clever: it changes
the command on the fly to TEST UNIT READY and tries to requeue the
original command. Sadly this breaks SCSI compability and of course
the midlayer is getting a bit confused by it.

So we're just removing that bit of code and let the midlayer deal with
it. It's clever enough by now. And the driver code is getting simpler.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>