Fix NPE on DefaultVirtualPacketProvider deactivate

Change-Id: I11123ddc5db2efd2da08e74f1bd6b006ba78f063
diff --git a/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProvider.java b/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProvider.java
index 5e65d94..36b4397 100644
--- a/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProvider.java
+++ b/incubator/net/src/main/java/org/onosproject/incubator/net/virtual/impl/provider/DefaultVirtualPacketProvider.java
@@ -110,7 +110,9 @@
 
     @Deactivate
     public void deactivate() {
-        packetService.removeProcessor(processor);
+        if (processor != null) {
+            packetService.removeProcessor(processor);
+        }
     }
 
     @Modified