[SCSI] sd_dif: problem with verify of type 1 protection information (PI)

It appears to me that there is a problem with handling of type 1 protection
information.

It is considering a logical block reference tag of 0xffffffff to be an error,
but it is actually valid any time ((lba & 0xffffffff) == 0xffffffff) [for
example, 2TiB-1, 4TiB-1, 6TiB-1, etc.].

I'm going by what's written in 4.18.3 of SBC3, where there doesn't appear
to be any invalid value for the reference tag.

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