RDMA/nes: Remove unneeded variable

Just a small cleanup.  The "passive_state" variable isn't used any
more after commit dae58728 ("RDMA/nes: Fix double CLOSE event
indication crash")

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Faisal Latif <faisal.latif@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>