Explicitly log when disconnecting a switch.

Change-Id: Ie52db282ce6856705e32175558630d37b7f93336
diff --git a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFChannelHandler.java b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFChannelHandler.java
index 7131242..624bea4 100644
--- a/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFChannelHandler.java
+++ b/protocols/openflow/ctl/src/main/java/org/onosproject/openflow/controller/impl/OFChannelHandler.java
@@ -744,6 +744,7 @@
          */
         protected void logErrorDisconnect(OFChannelHandler h, OFErrorMsg error) {
             logError(h, error);
+            log.error("Disconnecting switch {}", h.getSwitchInfoString());
             h.channel.disconnect();
         }