sata_nv: complain on spurious completion notifiers

Recently Tejun wrote a patch to ahci.c to make it raise a HSM violation
if the drive attempted to complete a tag that wasn't outstanding. We could
run into the same problem with sata_nv ADMA. This adds code to raise a HSM
violation error if the controller gives us a notifier tag that isn't
outstanding, since the drive may be issuing spurious completions.

Signed-off-by: Robert Hancock <hancockr@shaw.ca>
Signed-off-by: Jeff Garzik <jeff@garzik.org>