Correctly insert a drop action for empty treatment

It seems to me that the if-block between line 73 to 80 is ineffective in current implementation

Change-Id: Ia28fc9c7c4aace7c60f67a7926ba451e2236c4c8
diff --git a/drivers/src/main/java/org/onosproject/driver/pipeline/DefaultSingleTablePipeline.java b/drivers/src/main/java/org/onosproject/driver/pipeline/DefaultSingleTablePipeline.java
index d204938..d42650f 100644
--- a/drivers/src/main/java/org/onosproject/driver/pipeline/DefaultSingleTablePipeline.java
+++ b/drivers/src/main/java/org/onosproject/driver/pipeline/DefaultSingleTablePipeline.java
@@ -82,7 +82,7 @@
         FlowRule.Builder ruleBuilder = DefaultFlowRule.builder()
                 .forDevice(deviceId)
                 .withSelector(selector)
-                .withTreatment(fwd.treatment())
+                .withTreatment(treatment)
                 .fromApp(fwd.appId())
                 .withPriority(fwd.priority());