hw/riscv/virt: Add the BDF of IOMMU to RISCVVirtState structure

hw/riscv/virt: Add the BDF of IOMMU to RISCVVirtState structure

When the IOMMU is implemented as a PCI device, its BDF is created
locally in virt.c. However, the same BDF is also required in
virt-acpi-build.c to support ACPI. Therefore, make this information part
of the global RISCVVirtState structure so that it can be accessed
outside of virt.c as well.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20250322043139.2003479-2-sunilvl@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>