The current protocol was card-emulation specific. The new protocol is
generic/flexible enough to accommodate both tracing and card emulation,
as well as modem control and other future extensions.
We now auto-discover the end-point addresses based on the interface
descriptor. The user can also use the new "--interface" command line
argument to set a non-zero intrerface. In combination, this should
enable support for the remote-sim functionality on the second UART
on OWHW.