[SCSI] scsi_debug: GET LBA STATUS response length correction

The SCSI GET LBA STATUS command was introduced in SBC-3 revision
20 in September 2009. At that time the Parameter Data Length
field in the response had an associated byte offset of 8.

Then in SBC-3 revision 25 (October 2010) that byte offset was
changed to 4. The sg_get_lba_status utility in sg3_utils version
1.33 (released earlier today) has been changed to calculate
the newer response length. However the implementation of
GET LBA STATUS command in the scsi_debug driver still uses the
original byte offset.

modify the Parameter Data Length field value in the GET LBA STATUS command
response to comply with the change in SBC-3 revision 25

Signed-off-by: James Bottomley <JBottomley@Parallels.com>