hw/arm/virt-acpi-build.c: Migrate virtio creation to common location

hw/arm/virt-acpi-build.c: Migrate virtio creation to common location

RISC-V also needs to create the virtio in DSDT in the same way as ARM.
So, instead of duplicating the code, move this function to the device
specific file which is common across architectures.

Suggested-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20231218150247.466427-3-sunilvl@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>