Add support for the Qualcomm Robotics (RB3) dev kit, the Thundercomm
DB845c. This is a successor to the arrow 410c board already supported in
postmarketOS. It is based on the SDA845 SoC, almost identical to SDM845
but without a fully featured modem.

All the things you'd expect to work out of the box:
* UART
* USB host and peripheral
* HDMI display out
* Wifi, Bluetooth