xfs: cleanup buftarg handling in XFS_IOC_VERIFY_MEDIA

xfs: cleanup buftarg handling in XFS_IOC_VERIFY_MEDIA

The newly added XFS_IOC_VERIFY_MEDIA is a bit unusual in how it handles
buftarg fields.  Update it to be more in line with other XFS code:

 - use btp->bt_dev instead of btp->bt_bdev->bd_dev to retrieve the device
   number for tracing
 - use btp->bt_logical_sectorsize instead of
   bdev_logical_block_size(btp->bt_bdev) to retrieve the logical sector
   size
 - compare the buftarg and not the bdev to see if there is a separate
   log buftarg

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