format should trust blkdev
Currently, when using format(1M) on a blkdev device, it will ask all kinds of weird questions about the device: physical cylinders, bytes per track, RPM, ...
Most if not all don't apply to blkdev devices anyway, and it's unlikely that the user even knows what to enter there. Just like for SCSI, ATA, and VBD devices, format(1M) just shouldn't ask those questions to begin with.
This is related to RFE 2079.