arm64: dts: mt7986: add Bananapi R3

arm64: dts: mt7986: add Bananapi R3

Add support for Bananapi R3 SBC.

- SD/eMMC support (switching first 4 bits of data-bus with sw6/D)
- SPI-NAND/NOR support (switched CS by sw5/C)
- all rj45 ports and both SFP working (eth1/lan4)
- all USB-Ports + SIM-Slot tested
- i2c and all uarts tested
- wifi tested (with eeprom calibration data)

The device can boot from all 4 storage options. Both, SPI and MMC, can
be switched using hardware switches on the board, see
https://wiki.banana-pi.org/Banana_Pi_BPI-R3#Jumper_setting

Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20230106152845.88717-6-linux@fw-web.de
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>