xfs_scrub: drop SCSI_VERIFY code from disk.

xfs_scrub: drop SCSI_VERIFY code from disk.

Now that we have a media verification ioctl in the kernel, drop the
SCSI_VERIFY code, which enables us to drop the dependency on sg and
obviates the need to fix some unit-handling bugs in the HDIO_GETGEO
code.

A subsequent patch will enable larger verification IO sizes, which this
old code cannot handle.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>