Error message references incorrect variable

In remove_iscsi_target() for the TgtAdm class, the "Failed to
create iscsi target for volume id:" message references a
variable that doesn't exist -- use the correct variable name.

Fixes bug 1065073.

Change-Id: I55acb0dd2ee368fdc62a0ded6280d7ef7cd8ab7f

cinder/volume/iscsi.py

@@ -165,7 +165,7 @@ def remove_iscsi_target(self, tid, lun, vol_id, **kwargs):
                           run_as_root=True)
         except exception.ProcessExecutionError, e:
             LOG.error(_("Failed to create iscsi target for volume "
-                        "id:%(volume_id)s.") % locals())
+                        "id:%(vol_id)s.") % locals())
             raise exception.ISCSITargetRemoveFailed(volume_id=vol_id)
 
         os.unlink(volume_path)