hw/riscv/virt-acpi-build.c: Add namespace devices for PLIC and APLIC

hw/riscv/virt-acpi-build.c: Add namespace devices for PLIC and APLIC

As per the requirement ACPI_080 in the RISC-V Boot and Runtime Services
(BRS) specification [1],  PLIC and APLIC should be in namespace as well.
So, add them using the defined HID.

[1] - https://github.com/riscv-non-isa/riscv-brs/releases/download/v0.0.2/riscv-brs-spec.pdf
      (Chapter 6)

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20240716144306.2432257-2-sunilvl@ventanamicro.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>