Revert "Packet out buffer id should be -1 when there is no buffer"

This reverts commit 4d89266604bf4bd6ad18832475f6c7dbaf84b288.
diff --git a/src/python/loxi/of10/message.py b/src/python/loxi/of10/message.py
index d3a9f57..d80dac3 100644
--- a/src/python/loxi/of10/message.py
+++ b/src/python/loxi/of10/message.py
@@ -3781,7 +3781,7 @@
         if buffer_id != None:
             self.buffer_id = buffer_id
         else:
-            self.buffer_id = 0xffffffff
+            self.buffer_id = 0
         if in_port != None:
             self.in_port = in_port
         else: