scsi_debug v 1.75

From: 	Douglas Gilbert <dougg@torque.net>

    - fix highmem data transfers
         - fix kunmap_atomic() argument
         - disable clustering
    - allow every_nth < 0 for error continuously once
      count is reached
    - minor sense buffer handling cleanup
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>