GD32VF103

[Niibe Yutaka]

Hello,

I got a board with GD32VF103 (named Longan Nano), which has a 32-bit
RISC-V core and GD's peripherals.  Please note that while GD32F103 is
STM32F103 clone-like with ARM Cortex-M3 core, GD32VF103 comes with RV32
IMAC core.

For technical resources, I found the repo for the chip:

    https://github.com/riscv-mcu/

Looking the manual of GD32VF103, the USB peripheral is not the one of
GD32F103 but it has functionality of USB OTG (both of host and
function).

When it is configured by BOOT0/BOOT1 pins, it can be seen as USB DFU
board.  I accessed it by dfu-util.
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