SoC: Add support for StarFive JH7100 RISC-V SoC This adds support for the StarFive JH7100, including the necessary device drivers and DT files for the BeagleV Starlight prototype board, with additional boards to be added later. This SoC promises to be the first usable low-cost platform for RISC-V. I've taken this through the SoC tree in the anticipation of adding a few other Arm based SoCs as well, but those did not pass the review in time, so it's only this one.