hw/riscv/virt: virt-acpi-build.c: Add RINTC in MADT

Add Multiple APIC Description Table (MADT) with the
RINTC structure for each cpu.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Message-ID: <20230302091212.999767-6-sunilvl@ventanamicro.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>