Add hardware: Allwinner D1 (RISC-V-based)

[fengyuentau]

Hardware: Allwinner D1
Arch: RISC-V
Documents:

• English: https://d1.docs.aw-ol.com/en/; Chinese: https://d1.docs.aw-ol.com/
• Cross-compiling OpenCV for RISC-V arch: link (Chinese)

Notes:

• Python support is not complete enough, so only provide benchmark result of YuNet on this board.

[fengyuentau]

Due to the very limited Python support on the Allwinner D1 development board, the benchmark is converted to C++ (https://github.com/fengyuentau/opencv_zoo_cpp) and supports YuNet for now.