Target/iser: Avoid calling rdma_disconnect twice

rdma_disconnect may be called in 2 code flows:
- isert_wait_conn: disconnect initiated be the target
- disconnected_handler: disconnect invoked by the initiator

In case isert_conn->disconnect is true then rdma_disconnect
was called in disconnected handler, no need to call it again
from isert_wait_conn.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/infiniband/ulp/isert/ib_isert.c

@@ -3215,7 +3215,7 @@ static void isert_wait_conn(struct iscsi_conn *conn)
 	pr_debug("isert_wait_conn: Starting \n");
 
 	mutex_lock(&isert_conn->conn_mutex);
-	if (isert_conn->conn_cm_id) {
+	if (isert_conn->conn_cm_id && !isert_conn->disconnect) {
 		pr_debug("Calling rdma_disconnect from isert_wait_conn\n");
 		rdma_disconnect(isert_conn->conn_cm_id);
 	}