redhat/configs: automotive: builtin virtio-mmio

In some emulated environment (e.g QEMU w/ u-boot), virtio devices are
described in the device-tree under the transport compatible virtio,mmio,
including for the virtio_blk backend.

A previous MR builtin virtio_blk for bootspeed improvement:
redhat/centos-stream/src/kernel/centos-stream-9!3664 (merged)

Follow the same logic for virtio_mmio to match the behavior between
environments.

Signed-off-by: Eric Chanudet echanude@redhat.com