install_litex-ulx3s.sh fails after introduction of vendor prefix for ulx3s in litex-boards

[teletoby]

The ulx3s platform / target in litex-boards has a vendor prefix now. Therefore, the installation script install_litex-ulx3s.sh fails. The new name is radiona_ulx3s.py.

INFO:SoC:Initializing ROM rom with contents (Size: 0x868c).
INFO:SoC:Auto-Resizing ROM rom from 0x10000 to 0x868c.
Ok! Exit code = [0] using params=
calling ./ulx3s.py --device LFE5U-85F from /home/toby/ULX3S_workspace/litex-boards/litex_boards/targets
./install_litex-ulx3s.sh: line 43: ./ulx3s.py: No such file or directory
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Looking in /home/toby/ULX3S_workspace/install_logs/install_litex-ulx3s_20210524_160725.log for errors...
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Error detected. Try updating dependencies. Press enter to continue, or Ctrl-C to abort.
~/ULX3S_workspace/ulx3s-toolchain
Completed ./install_litex-ulx3s.sh