Fix a bug in ncr_freeze_devq() which is called when we see a queue

Fix a bug in ncr_freeze_devq() which is called when we see a queue
full condition or other error which requires us to purge the
controller's start queue of transactions for a particular device.
We were relying on the NCR CCB's program address to cause the
script engine to skip to the next entry in the queue even though
the CCB is freed (and its program address switched to the idle
loop) by this action.  We now set the address in the start queue
to be the "skip" function directly.