hw/i386/acpi-microvm.c: Use common function to add virtio in DSDT

hw/i386/acpi-microvm.c: Use common function to add virtio in DSDT

With common function to add virtio in DSDT created now, update microvm
code also to use it instead of duplicate code.

Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20231218150247.466427-4-sunilvl@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>