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

arch/riscv/Kconfig

arch/riscv/cpu/fu540/Kconfig

arch/riscv/cpu/fu740/Kconfig

arch/riscv/cpu/fu740/Makefile

arch/riscv/cpu/fu740/cache.c

arch/riscv/cpu/fu740/cpu.c

arch/riscv/cpu/fu740/dram.c

arch/riscv/cpu/fu740/spl.c

arch/riscv/dts/Makefile

arch/riscv/dts/fu740-c000-u-boot.dtsi

arch/riscv/dts/fu740-c000.dtsi

arch/riscv/dts/fu740-hifive-unmatched-a00-ddr.dtsi

arch/riscv/dts/hifive-unmatched-a00-u-boot.dtsi

arch/riscv/dts/hifive-unmatched-a00.dts

arch/riscv/include/asm/arch-fu740/cache.h

arch/riscv/include/asm/arch-fu740/clk.h

arch/riscv/include/asm/arch-fu740/gpio.h

arch/riscv/include/asm/arch-fu740/reset.h

arch/riscv/include/asm/arch-fu740/spl.h

board/sifive/unleashed/Kconfig