Various fixes to get a P4Runtime demo that works

Change-Id: Icab512fceeb6ec0faf1b402c1e325e055cdb2caf
diff --git a/protocols/p4runtime/ctl/src/main/java/org/onosproject/p4runtime/ctl/P4RuntimeControllerImpl.java b/protocols/p4runtime/ctl/src/main/java/org/onosproject/p4runtime/ctl/P4RuntimeControllerImpl.java
index d134a22..277af11 100644
--- a/protocols/p4runtime/ctl/src/main/java/org/onosproject/p4runtime/ctl/P4RuntimeControllerImpl.java
+++ b/protocols/p4runtime/ctl/src/main/java/org/onosproject/p4runtime/ctl/P4RuntimeControllerImpl.java
@@ -67,6 +67,7 @@
 
     @Activate
     public void activate() {
+        eventDispatcher.addSink(P4RuntimeEvent.class, listenerRegistry);
         log.info("Started");
     }
 
@@ -74,6 +75,7 @@
     @Deactivate
     public void deactivate() {
         grpcController = null;
+        eventDispatcher.removeSink(P4RuntimeEvent.class);
         log.info("Stopped");
     }