[SCSI] sd: Allow protection_type to be overridden

We have encountered a few devices that misbehaved when operating in T10
PI mode. Allow T10 PI protection type to be overridden from userland.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>