- add sense data helper functions:
   - scsi_sense_desc_find() to find a given
     sense descriptor (e.g. type 0 -> information)
   - scsi_get_sense_info_fld() to get the information
     field from fixed or descriptor sense data

Kai Makisara proposed the "find" function. For
example, it will help the st driver find the Filemark,
EOM and ILI flags which have been placed in the
"stream commands" sense data descriptor.
Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>