loxi-prep: remove uses of cstruct module
This module does not exist in PyLoxi.
diff --git a/tests/openflow_protocol_messages.py b/tests/openflow_protocol_messages.py
index b182015..81b1e05 100644
--- a/tests/openflow_protocol_messages.py
+++ b/tests/openflow_protocol_messages.py
@@ -12,7 +12,7 @@
from oftest import config
import oftest.controller as controller
-import oftest.cstruct as ofp
+import ofp
import oftest.message as message
import oftest.dataplane as dataplane
import oftest.action as action