Merge https://source.denx.de/u-boot/custodians/u-boot-riscv

CI: https://source.denx.de/u-boot/custodians/u-boot-riscv/-/pipelines/24215

- RISC-V: Add "riscv,isa-extensions" and multi-letter extension parsing
  support
- RISC-V: Add default cache line size
- Board: Canaan: Add K230-CanMV support
- Board: VisionFive2: Split out target specific configuration