General link discovery module cleanup.

* Removed all events we don't use from the event system (switch and port
  events, link updates)
* Refactored event interface to two separate methods to match the other event
  interfaces
* Removed the LDUpdate class and moved all the event enums and classes to be
  internal to the LinkDiscoveryManager
* Removed all LinkTypes we no longer used and moved the one remaining type
  to the ILinkDiscoveryService. After this the ILinkDiscovery interface is
  no longer needed.
* Made Link immutable
* Removed the linkdiscovery.internal package as it only contained one class
* Readability improvements to LinkDiscoveryManager

Change-Id: Ifae97879aadc49b70a7b3d2294dcc540538c2cfc
diff --git a/src/main/java/net/floodlightcontroller/core/internal/Controller.java b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
index 7374803..ae362a2 100644
--- a/src/main/java/net/floodlightcontroller/core/internal/Controller.java
+++ b/src/main/java/net/floodlightcontroller/core/internal/Controller.java
@@ -1088,7 +1088,7 @@
             // and attempted to be written to the database before the port is in
             // the database. We now suppress link discovery on ports until we're
             // sure they're in the database.
-            linkDiscovery.addToSuppressLLDPs(sw.getId(), port.getPortNumber());
+            linkDiscovery.disableDiscoveryOnPort(sw.getId(), port.getPortNumber());
 
             sw.setPort(port);
             SwitchUpdate update = new SwitchUpdate(sw, port, SwitchUpdateType.PORTADDED);
@@ -1341,7 +1341,7 @@
         // the database. We now suppress link discovery on ports until we're
         // sure they're in the database.
         for (OFPhysicalPort port : sw.getPorts()) {
-            linkDiscovery.addToSuppressLLDPs(sw.getId(), port.getPortNumber());
+            linkDiscovery.disableDiscoveryOnPort(sw.getId(), port.getPortNumber());
         }
 
         // TODO: is it safe to modify the HashMap without holding