That's already been done by the virtio infrastructure before the probe
function is called.

Reported-by: alexey.kardashevskiy@au1.ibm.com
Acked-by: NAmit Shah <amit.shah@redhat.com>
Tested-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>