script/traffic_replay: print packets data to stderr

This is debug info, should print to stderr.
Otherwise it will flood stdout.

Signed-off-by: Joe Guo <joeg@catalyst.net.nz>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

script/traffic_replay

@@ -272,9 +272,9 @@ def main():
     if opts.debuglevel > 5:
         for c in conversations:
             for p in c.packets:
-                print("    ", p)
+                print("    ", p, file=sys.stderr)
 
-        print('=' * 72)
+        print('=' * 72, file=sys.stderr)
 
     if opts.number_of_users and opts.number_of_users < len(conversations):
         print_err(("--number-of-users (%d) is less than the "