RDMA/nes: Fix hang with modified FIN handling on A0 cards

Changing state to CLOSING when FIN is received causes A0 cards to
hang.  Fix this by checking for A0 cards in FIN handling.

Signed-off-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>