[Falcon] link discovery -

- Support for TLV containing cluster fingerprint info
- Config for enabling extra TLV at device level
- Refactored ONOSLLDP constructor for ease of use

Change-Id: I93abe6c0ed8b7e37c80af5920649272faad8856e
diff --git a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java
index a9da92a..04729e4 100644
--- a/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java
+++ b/providers/lldp/src/main/java/org/onosproject/provider/lldp/impl/DiscoveryContext.java
@@ -66,4 +66,11 @@
      * @param key link key
      */
     void touchLink(LinkKey key);
+
+    /**
+     * Returns the cluster-wide unique identifier.
+     *
+     * @return the cluster identifier
+     */
+    String fingerprint();
 }