staging: lustre: llite: enable clients to inject error for lfsck

This enables the client to inject an error by altering
the parent FID in order to test if the server side file
system checker behaves properly.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3951
Reviewed-on: http://review.whamcloud.com/7667


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>