Add support for the Alibaba Cloud AS02MC04 Kintex UltraScale+ PCIe board

[dkozel]

I'm starting to add support for this PCIe accelerator board as it is currently available inexpensively on eBay and Aliexpress. It had a Xilinx KU3P FPGA, which is supported by Vivado's zero cost license.

Some basic documentation and reverse engineering has been done by other people:

https://essenceia.github.io/projects/alibaba_cloud_fpga/
https://gist.github.com/Chester-Gillon/765d6286b1c34c7dc26a7b4c4dd0c48c

I'm collecting the info from external posts and will make some test projects and notes here:
https://github.com/dkozel/Alibaba-Cloud-FPGA

The current status of my board addition is here:

platforms/alibaba_xcku3p.py
targets/alibaba_xcku3p.py

Todo:

• Resolve basic build issues
• Add JTAG UART support for Ultrascale+
• Test LED chaser
• Add LiteScope example
• Add QSPI Flash
• Test SFP+ interfaces up to 25 Gb/s Ethernet
• Test PCIe Gen3 up to x8
• ??
• Document how to Add a new board