ionic: add lif_quiesce to wait for queue activity to stop

Even though we've already turned off the queue activity with
the ionic_qcq_disable(), we need to wait for any device queues
that are processing packets to drain down before we try to
flush our packets and tear down the queues.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>