openflow_input: use padding member syntax
diff --git a/openflow_input/nicira_dec_ttl b/openflow_input/nicira_dec_ttl
index 6d113fb..33a80a6 100644
--- a/openflow_input/nicira_dec_ttl
+++ b/openflow_input/nicira_dec_ttl
@@ -32,6 +32,6 @@
     uint16_t len;
     uint32_t experimenter;    // OF_EXPERIMENTER_ID_NICIRA
     uint16_t subtype;         // 18
-    uint16_t pad;
-    uint32_t pad2;
+    pad(2);
+    pad(4);
 };