[PATCH 3/3] nvme: make SG_IO support optional

[Sagi Grimberg]

> Translation SCSI commands to NVMe commands is rather pointless in general
> as applications must not expext to be able to use SCSI commands on a
> generic block device.
>
> Make the huge translation layer optional and hope no one will ever enable
> it in the future.

Umm, this is needed to support multipathing (at least in the multipath
daemon current form). I'm not sure this is a good idea just yet...