LU-6831 lmv: revalidate the dentry for striped dir

LU-6831 lmv: revalidate the dentry for striped dir

If there are bad stripe during striped dir revalidation,
most likely due the race between close(unlink) and
getattr, then let's revalidate the dentry, instead of
return error, like normal directory.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I410940473d123796f75607d39153240b7d3f737b
Reviewed-on: http://review.whamcloud.com/15720
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>