Running upstream OpenSBI on SpacemiT K1

The SpacemiT K1 is a rather interesting RISC-V SoC, found for instance on boards like the Banana Pi BPI-F3 board. It's one of those platforms that looked promising on paper, but took a bit of time before things really started to move upstream. Things have clearly accelerated over the last few months. Linux 7.0 brings, among other things PCIe support, making the board quite capable as a development…