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

MAINTAINERS

arch/riscv/dts/k210-maix-bit.dts

arch/riscv/dts/k210.dtsi

board/sipeed/maix/maix.c

doc/board/sipeed/maix.rst

doc/device-tree-bindings/mfd/canaan,k210-sysctl.txt

doc/device-tree-bindings/pinctrl/canaan,k210-fpioa.txt

doc/device-tree-bindings/spi/snps,dw-apb-ssi.txt

drivers/clk/Makefile

drivers/clk/clk_k210.c

drivers/pinctrl/Makefile

drivers/pinctrl/pinctrl-k210.c

drivers/spi/designware_spi.c

include/configs/sipeed-maix.h

include/k210/pll.h

test/dm/k210_pll.c