Add code for FPGA side of bsg_link

[taylor-bsg]

basejump_stl/hard/ultrascale_plus/bsg_link/README.md

Line 1 in 321c896

This directory contains the FPGA side of the bsg_link.

Hi Paul, I noticed that we don't have the FPGA code for bsg_link -- do you think you can add it? I assume that as we build the HB daughterboard, this will be a component we use. This will also be very useful for external users of the bsg_link module.

[taylor-bsg]

@gaozihou also would it make sense to have a FPGA bsg_tag component with STA constraints?

[dpetrisko]

@gaozihou additional info that would be helpful: max speed of clock/data pins achieved on FPGA, and if there are any board-level tricks required for that