OneFS now fails to attach instead of failing the assertion and panicking.
```
virtio_pci0: <VirtIO PCI SCSI adapter> port 0x2000-0x203f mem 0xc0000000-0xc0001fff irq 16 at device 4.0 on pci0
vtscsi0: <VirtIO SCSI Adapter> on virtio_pci0
vtscsi0: max_nsegs is too big (66 > 64)
device_attach: vtscsi0 attach returned 7
```
Vanilla FreeBSD head seems unaffected.