platforms: Add ice40_hx8k_b_evn platform.
platforms: Add ice40_hx8k_b_evn platform.

:000000 100644 0000000 487d352 A	platforms/ice40_hx8k_b_evn.py

:000000 100644 0000000 5bc543f A	platforms/ice40_hx8k_b_evn.py

mithro/HDMI2USB-litex-firmware,mithro/HDMI2USB-litex-firmware,mithro/HDMI2USB-litex-firmware,mithro/HDMI2USB-litex-firmware