RDMA/nes: Don't call event handler if pointer is NULL

Don't call the ibqp event_handler pointer in the case it wasn't initialized.
Signed-off-by: Tatyana Nikolova <Tatyana.E.Nikolova@intel.com>
Signed-off-by: Donald Wood <Donald.E.Wood@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/nes/nes_cm.c

@@ -2884,6 +2884,7 @@ static int nes_cm_disconn_true(struct nes_qp *nesqp)
 			ibevent.device = nesqp->ibqp.device;
 			ibevent.event = nesqp->terminate_eventtype;
 			ibevent.element.qp = &nesqp->ibqp;
+			if (nesqp->ibqp.event_handler)
 				nesqp->ibqp.event_handler(&ibevent, nesqp->ibqp.qp_context);
 		}
 	}