hw/riscv/virt: Add OEM_ID and OEM_TABLE_ID fields

hw/riscv/virt: Add OEM_ID and OEM_TABLE_ID fields

ACPI needs OEM_ID and OEM_TABLE_ID for the machine. Add these fields
in the RISCVVirtState structure and initialize with default values.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20230302091212.999767-2-sunilvl@ventanamicro.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>