openflow_input: use of_ prefix in input files

No change to generated code.
diff --git a/openflow_input/bsn_set_tunnel_dst b/openflow_input/bsn_set_tunnel_dst
index 6b16d96..79e57b3 100644
--- a/openflow_input/bsn_set_tunnel_dst
+++ b/openflow_input/bsn_set_tunnel_dst
@@ -28,7 +28,7 @@
 #version any
 
 // BSN set tunnel destination IP action
-struct ofp_action_bsn_set_tunnel_dst {
+struct of_action_bsn_set_tunnel_dst {
     uint16_t type;      // OF_ACTION_TYPE_EXPERIMENTER
     uint16_t len;
     uint32_t experimenter;    // OF_EXPERIMENTER_ID_BSN