ONOS-3206 refactoring LLDP link provider.

- refactoring to unify LinkDiscovery helper instantiation
- Support suppression rule update at runtime

Change-Id: I2a6db6e82fcb90ee5635f0ac09564efd55276ebf
diff --git a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
index 8cdfd50..7dc9aed 100644
--- a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
+++ b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/LinkDiscovery.java
@@ -61,7 +61,7 @@
 
     private final ONOSLLDP lldpPacket;
     private final Ethernet ethPacket;
-    private Ethernet bddpEth;
+    private final Ethernet bddpEth;
 
     private Timeout timeout;
     private volatile boolean isStopped;
@@ -126,7 +126,7 @@
     }
 
     /**
-     * Add physical port port to discovery process.
+     * Add physical port to discovery process.
      * Send out initial LLDP and label it as slow port.
      *
      * @param port the port
@@ -141,6 +141,14 @@
     }
 
     /**
+     * removed physical port from discovery process.
+     * @param port the port number
+     */
+    void removePort(PortNumber port) {
+        ports.remove(port.toLong());
+    }
+
+    /**
      * Handles an incoming LLDP packet. Creates link in topology and adds the
      * link for staleness tracking.
      *