openflow_input: declare of_flowmod.flags as enum ofp_flow_mod_flags

others will follow
diff --git a/openflow_input/standard-1.2 b/openflow_input/standard-1.2
index bfa9a64..703a969 100644
--- a/openflow_input/standard-1.2
+++ b/openflow_input/standard-1.2
@@ -772,7 +772,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;
@@ -793,7 +793,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;
@@ -814,7 +814,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;
@@ -835,7 +835,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;
@@ -856,7 +856,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;
@@ -877,7 +877,7 @@
     uint32_t buffer_id;
     of_port_no_t out_port;
     uint32_t out_group;
-    uint16_t flags;
+    ofp_flow_mod_flags flags;
     pad(2);
     of_match_t match;
     list(of_instruction_t) instructions;