RDMA/nes: Fix client side QP destroy

Fix QP not being destroyed properly on the client, which leads to
userspace programs hanging on exit.  This is a missing chunk from the
connection management rewrite in commit 6492cdf3 ("RDMA/nes: CM
connection setup/teardown rework").

Signed-off-by: Faisal Latif <flatif@neteffect.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>