Add devicetree for Bananapi R3 Mini SBC.

Key features:
- MediaTek MT7986A(Filogic 830) Quad core ARM Cortex A53
- Wifi 6 2.4G/5G (MT7976C)
- 2G DDR RAM
- 8G eMMC flash
- 128MB Nand flash
- 2x 2.5GbE network port
- 1x M.2 Key B USB interface
- 1x M.2 KEY M PCIe interface
- 1x USB2.0 interface

source: https://wiki.banana-pi.org/Banana_Pi_BPI-R3_MiniCo-developed-by: Eric Woudstra <ericwouds@gmail.com>
Signed-off-by: Eric Woudstra <ericwouds@gmail.com>
Co-developed-by: Tianling Shen <cnsztl@gmail.com>
Signed-off-by: Tianling Shen <cnsztl@gmail.com>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240510095707.6895-3-linux@fw-web.deSigned-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>