packetforge: fix GTP-Extension header field data

Fix the incorrect fields data of GTP-Extension header.

Type: fix
Signed-off-by: Ting Xu <ting.xu@intel.com>
Change-Id: Iafc5e852910649afcf0e583a5513b1ab33f5b5e8
diff --git a/extras/packetforge/parsegraph/nodes/gtppsc.json b/extras/packetforge/parsegraph/nodes/gtppsc.json
index d6814be..bf0ac11 100644
--- a/extras/packetforge/parsegraph/nodes/gtppsc.json
+++ b/extras/packetforge/parsegraph/nodes/gtppsc.json
@@ -4,7 +4,7 @@
     "layout" : [
         {
             "name" : "length",
-            "size" : "1",
+            "size" : "8",
             "default" : "1",
             "readonly" : "true"
         },
@@ -23,6 +23,10 @@
         {
             "name" : "qfi",
             "size" : "6"
+        },
+        {
+            "name" : "nextext",
+            "size" : "8"
         }
     ]
 }