hw/riscv/virt.c: add cbo[mz]-block-size fdt properties

hw/riscv/virt.c: add cbo[mz]-block-size fdt properties

The cbom-block-size fdt property property is used to inform the OS about
the blocksize in bytes for the Zicbom cache operations. Linux documents
it in Documentation/devicetree/bindings/riscv/cpus.yaml
as:

  riscv,cbom-block-size:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      The blocksize in bytes for the Zicbom cache operations.

cboz-block-size has the same role but for the Zicboz extension, i.e.
informs the size in bytes for Zicboz cache operations. Linux support
for it is under review/approval in [1]. Patch 3 of that series describes
cboz-block-size as:

  riscv,cboz-block-size:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      The blocksize in bytes for the Zicboz cache operations.

[1] https://lore.kernel.org/all/20230224162631.405473-1-ajones@ventanamicro.com/

Cc: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Message-ID: <20230302091406.407824-2-dbarboza@ventanamicro.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>