openflow_input: use of_ prefix in input files

No change to generated code.
diff --git a/openflow_input/bsn_get_interfaces b/openflow_input/bsn_get_interfaces
index 90060ee..f170d6f 100644
--- a/openflow_input/bsn_get_interfaces
+++ b/openflow_input/bsn_get_interfaces
@@ -27,7 +27,7 @@
 
 #version any
 
-struct ofp_bsn_get_interfaces_request {
+struct of_bsn_get_interfaces_request {
     uint8_t version;
     uint8_t type;
     uint16_t length;
@@ -36,7 +36,7 @@
     uint32_t subtype;   // BSN_GET_INTERFACES_REQUEST
 };
 
-struct ofp_bsn_interface {
+struct of_bsn_interface {
     of_mac_addr_t hw_addr;
     uint16_t pad;
     of_port_name_t name;
@@ -44,7 +44,7 @@
     uint32_t ipv4_netmask;
 };
 
-struct ofp_bsn_get_interfaces_reply {
+struct of_bsn_get_interfaces_reply {
     uint8_t version;
     uint8_t type;
     uint16_t length;