Remove bogus unref in virDBusMessageRead

The virDBusMessageRead method should not have side-effects on
the message parameter passed in, so unref'ing it is wrong.
The caller should unref only when they decided they are done
with it.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

src/util/virdbus.c

@@ -1421,7 +1421,6 @@ int virDBusMessageRead(DBusMessage *msg,
     ret = virDBusMessageDecodeArgs(msg, types, args);
     va_end(args);
 
-    dbus_message_unref(msg);
     return ret;
 }