Stream Message objects with data properly

We were streaming the message instead of data, causing an infinate
recursion and crash.  Not very helpful.

Change-Id: I01a97a719e6567452de9276265e9dfe3bc53c885
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/aos/events/logging/logfile_utils.cc b/aos/events/logging/logfile_utils.cc
index 9c8b7af..9c7fe5d 100644
--- a/aos/events/logging/logfile_utils.cc
+++ b/aos/events/logging/logfile_utils.cc
@@ -740,7 +740,7 @@
   os << "{.channel_index=" << m.channel_index
      << ", .queue_index=" << m.queue_index << ", .timestamp=" << m.timestamp;
   if (m.data != nullptr) {
-    os << ", .data=" << m;
+    os << ", .data=" << m.data;
   }
   os << "}";
   return os;