Remove unused QDBusMessage::timeout member

It's been there forever, but never used. The timeout is set during the
actual call.

I moved QDBusMessage::type only for padding purposes.

Change-Id: I41dd638ac423078be642077dbf17439d15b5d405
Reviewed-by: Richard J. Moore <rich@kde.org>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>