Fabric.p4 cherry-picks from onos-2.2

Publish fabric.p4 constants with fabric-api artifact

For consumption by third-party apps who wish to operate directly on
fabric.p4 tables and other entities.

(cherry picked from commit 8f6b5cdabf7828f6f7c017f288aad87c7bd0911a)

Backport fabric-tna dbuf support to v1model
(cherry picked from commit 4d1d67fa3abb4d7517e5836fbb82c899acffa951)

Update SPGW p4 namespace to match fabric-tna
(cherry picked from commit 35e4d196eb61104e7f96c62361a100bb454ee1cf)

Change-Id: I3230a508a601180060e1041d4369a54f519658e1
diff --git a/pipelines/fabric/impl/src/main/java/org/onosproject/pipelines/fabric/impl/behaviour/FabricCapabilities.java b/pipelines/fabric/impl/src/main/java/org/onosproject/pipelines/fabric/impl/behaviour/FabricCapabilities.java
index 19b3206..2eb947d 100644
--- a/pipelines/fabric/impl/src/main/java/org/onosproject/pipelines/fabric/impl/behaviour/FabricCapabilities.java
+++ b/pipelines/fabric/impl/src/main/java/org/onosproject/pipelines/fabric/impl/behaviour/FabricCapabilities.java
@@ -17,6 +17,7 @@
 package org.onosproject.pipelines.fabric.impl.behaviour;
 
 import org.onosproject.net.pi.model.PiPipeconf;
+import org.onosproject.pipelines.fabric.FabricConstants;
 import org.slf4j.Logger;
 
 import java.io.BufferedReader;