openflow_input: use of_ prefix in input files

No change to generated code.
diff --git a/openflow_input/bsn_table_mod b/openflow_input/bsn_table_mod
index 418c716..6161abf 100644
--- a/openflow_input/bsn_table_mod
+++ b/openflow_input/bsn_table_mod
@@ -29,7 +29,7 @@
 
 // This is the 1.1+ table mod message which we back port to 1.0
 // for use inside components
-struct ofp_table_mod {
+struct of_table_mod {
     uint8_t version;
     uint8_t type;
     uint16_t length;