DSCP values of the QoS object are not effective

DSCP value in the IP header of I/O frames is always zero. Seems like we set the DSCP values via SetSockOpt() when the QoS object is started, so they at least should be applicable after a type 0 reset. Most probably, these values have to be applied on a per-socket basis in the lwIP accept callback, just as it is done for all the other socket options.