[ONOS-2713] Fix a bug of ovsdb controller and add anotations.

Change-Id: I8ed9cee526b25e65d12fdb25ba98c281b1a33eff
diff --git a/ovsdb/ctl/src/main/java/org/onosproject/ovsdb/controller/impl/Controller.java b/ovsdb/ctl/src/main/java/org/onosproject/ovsdb/controller/impl/Controller.java
index cf3db9e..cd4d514 100644
--- a/ovsdb/ctl/src/main/java/org/onosproject/ovsdb/controller/impl/Controller.java
+++ b/ovsdb/ctl/src/main/java/org/onosproject/ovsdb/controller/impl/Controller.java
@@ -85,8 +85,7 @@
         b.option(ChannelOption.WRITE_BUFFER_LOW_WATER_MARK, 8 * 1024);
         b.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
         b.childOption(ChannelOption.SO_KEEPALIVE, true);
-        ChannelFuture cf = b.bind(ovsdbPort).sync();
-        cf.channel().closeFuture().sync();
+        b.bind(ovsdbPort).sync();
     }
 
     /**