It is possible to swap the CQs used for send_cq and recv_cq when
creating two different QPs.  If these two QPs are then destroyed at
the same time, an AB-BA deadlock can occur because the CQ locks are
taken our of order.  Fix this by always taking CQ locks in a fixed
order.
Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>