Add efinix Ti375 c529 dev kit support

[Dolu1990]

Don't merge before :

• build/efinix: add a few IO primitives, IO constraints, sdc rework enjoy-digital/litex#2060
• soc/cores/vexiiriscv: update clocks + add video framebuffer support enjoy-digital/litex#2059

This is the port i'm using mostly to run VexiiRiscv + Debian.

Typicaly with :
--cpu-type=vexiiriscv --cpu-variant=debian --update-repo=no --with-jtag-tap --with-sdcard --with-coherent-dma --with-ohci --vexii-video "name=video" --vexii-args="--fetch-l1-hardware-prefetch=nl --fetch-l1-refill-count=2 --fetch-l1-mem-data-width-min=128 --lsu-l1-mem-data-width-min=128 --lsu-software-prefetch --lsu-hardware-prefetch rpt --performance-counters 9 --lsu-l1-store-buffer-ops=32 --lsu-l1-refill-count 4 --lsu-l1-writeback-count 4 --lsu-l1-store-buffer-slots=4 --relaxed-div" --l2-bytes=524288 --sys-clk-freq 100000000 --cpu-clk-freq 200000000 --with-cpu-clk --bus-standard axi-lite --cpu-count=4 --build

It assums :

• debug jtag on PMOD0
• usb pmod on PMOD1
• Efinix HDMI extentions board on PMOD2

Note that it is fast <3
Memspeed at 0x40000000 (Sequential, 2.0MiB)...
Write speed: 562.2MiB/s
Read speed: 732.0MiB/s

[enjoy-digital]

Thanks @Dolu1990! We'll review the different PR and merge things progressively in the next days.

[enjoy-digital]

Now that the others PR are merged, we can also merge this. Thanks @Dolu1990!