platforms/ice40_up5k_b_evn: Move default serial port mapping to free pins (previous pins shared with switches).
platforms/ice40_up5k_b_evn: Move default serial port mapping to free pins (previous pins shared with switches).

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