The UDP loopback just reads from the input FIFO, reverses src and destination
addresses, and writes back to the output FIFO.
This can be used to measure the throughput of the HPS-FPGA communication
The Golden Hardware Reference Design (GHRD) is used to implement designs
with PS support.
The UDP/IP stack of the Linux running on the PS is used to move UDP packets
to/from the PL.
