Add support for NiteFury/LiteFury about microwatt

[mithro]

According to the sqrl_acron.py file in LiteX;

# The Acorn (CLE-101, CLE-215(+)) are cryptocurrency mining accelerator cards from SQRL that can be
# repurposed as generic FPGA PCIe development boards:
# - http://www.squirrelsresearch.com/acorn-cle-101
# - http://www.squirrelsresearch.com/acorn-cle-215-plus
# The 101 variant is eguivalent to the LiteFury and 215 variant equivalent to the NiteFury from
# RHSResearchLLC that are documented at: https://github.com/RHSResearchLLC/NiteFury-and-LiteFury.

LiteX also has a way to provide a UART over the PCIe bus (and also updating the bitstream).

Some random links;

• https://twitter.com/SeanMBlakley/status/1459971651504852998?s=20
• https://twitter.com/enjoy_digital/status/1462853379076628482?s=20
• https://twitter.com/gbuzogany/status/1470127685103927303?s=20
• https://twitter.com/enjoy_digital/status/1462876566531231751?s=20
• https://twitter.com/hansfbaier/status/1482977512879980545?s=20

[mithro]

• https://twitter.com/enjoy_digital/status/1480427484671795201?s=20 -- --uart-name=crossover

[mithro]

There seems to be a full set of instructions at https://teaandtechtime.com/litex-on-the-sqrl-acorn-fpga/

[mithro]

Even more;

• https://github.com/enjoy-digital/litex-acorn-baseboard
• https://github.com/Victoromoniyi/gr-litex
• https://github.com/SMB784/SQRL_quickstart