- revert the patch landed by mistake

i=adilger
i=eeb

 - improved sd iostats:
  * time requests spend in elevator's queue
  * time requests are served by disk
  * seek stats
  * queue depth stats

b=12755

Rollback 12755 since it breaks the SLES9 build.

b=12755
i=johann
i=shadow

Severity   : normal
Frequency  : when using more than 256 SCSI disks on a single server
Bugzilla   : 12755
Description: Kernel BUG: sd_iostats_bump: unexpected disk index
Details    : a kernel BUG is hit when using more than 256 SCSI disks.