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

- Update qemu-riscv.rst build instructions.
- Add support for SPI on Kendryte K210.
- Add Microchip PolarFire SoC Icicle Kit support.
- Add support for an early timer.
  - Select TIMER_EARLY to avoid infinite recursion for Trace.

diff --cc lib/Kconfig
Simple merge