Use log_trace to log non-running interfaces

This log message does spam the output of macnocker,
if an interface is down, because it is executed every second.

This is not a critical debug message, as it is expected behaviour,
so it is converted to log_trace, so it is only output when really
necessary

Signed-off-by: Fabian Bläse <fabian@blaese.de>

macnockclient.c

@@ -95,7 +95,7 @@ void macNockClient_run()
         if (!(ifr.ifr_flags & IFF_RUNNING))
         {
             // interface is not running, silently ignore
-            log_debug("[c] interface is not running\n");
+            log_trace("[c] interface is not running\n");
             goto retry;
         }