virtio_net: don't require ANY_LAYOUT with VERSION_1

ANY_LAYOUT is a compatibility feature. It's implied
for VERSION_1 devices, and non-transitional devices
might not offer it. Change code to behave accordingly.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>