riscv: dts: renesas: Add initial devicetree for Renesas RZ/Five SoC

riscv: dts: renesas: Add initial devicetree for Renesas RZ/Five SoC

Add initial device tree for Renesas RZ/Five RISC-V CPU Core (AX45MP
Single).

RZ/Five SoC is almost identical to RZ/G2UL Type-1 SoC (ARM64) hence we
will be reusing r9a07g043.dtsi [0] as a base DTSI for both the SoC's.
r9a07g043f.dtsi includes RZ/Five SoC specific blocks.

Below are the RZ/Five SoC specific blocks added in the initial DTSI which
can be used to boot via initramfs on RZ/Five SMARC EVK:
- AX45MP CPU
- PLIC

[0] arch/arm64/boot/dts/renesas/r9a07g043.dtsi

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20221028165921.94487-5-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>