Small fixes and improvements on fabric.p4
- setting s_tag and c_tag for BNG as early as possible in the pipeline
- ingress_port_vlan was matching on inner_vlan_tag but that field could be not present

Change-Id: Id4d51159a314d45cec370471ed244a51fd74338b
diff --git a/pipelines/fabric/impl/src/main/resources/include/header.p4 b/pipelines/fabric/impl/src/main/resources/include/header.p4
index b87237b..bea9619 100644
--- a/pipelines/fabric/impl/src/main/resources/include/header.p4
+++ b/pipelines/fabric/impl/src/main/resources/include/header.p4
@@ -162,10 +162,12 @@
 const bng_type_t BNG_TYPE_DOWNSTREAM = 2w0x2;;
 
 struct bng_meta_t {
-    bit<2>  type; // upstream or downstream
-    bit<32> line_id; // subscriber line
-    bit<16> pppoe_session_id;
-    bit<32> ds_meter_result; // for downstream metering
+    bit<2>    type; // upstream or downstream
+    bit<32>   line_id; // subscriber line
+    bit<16>   pppoe_session_id;
+    bit<32>   ds_meter_result; // for downstream metering
+    vlan_id_t s_tag;
+    vlan_id_t c_tag;
 }
 #endif // WITH_BNG