The UDP based forwarding really only ever was a quick hack to
demonstrate the capabilities.
Meanwhile, we've had the proper osmo-remsim project implemented,
which provides a much more reliable and comprehensive way of
managing SIM card emulation devices (SIMtrace2, sysmoQMOD, ...)
and collection of card readers (sysmoOCTSIM or any other PC/SC
supported readers).
Hence, remove the "UDP forwarding part.
Change-Id: Ia4b9447b95872b6e0dda6dca644f1ed4a87355a0