Lower log level for Kryo serializer id fallback message

Change-Id: If6d0cc891b7bfca096b3d3508f30f8516d3c103f
diff --git a/utils/misc/src/main/java/org/onlab/util/KryoNamespace.java b/utils/misc/src/main/java/org/onlab/util/KryoNamespace.java
index b5c3926..a8b1e16 100644
--- a/utils/misc/src/main/java/org/onlab/util/KryoNamespace.java
+++ b/utils/misc/src/main/java/org/onlab/util/KryoNamespace.java
@@ -430,7 +430,7 @@
             r = kryo.register(type, serializer, id);
         }
         if (r.getId() != id) {
-            log.info("{} already registed as {}. Skipping {}.",
+            log.debug("{} already registed as {}. Skipping {}.",
                      r.getType(), r.getId(), id);
         }
         log.trace("{} registered as {}", r.getType(), r.getId());