staging: lustre: lmv: release request in lmv_revalidate_slaves()

In lmv_revalidate_slaves() ensure that the request returned by
md_intent_lock() is properly released on all paths.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5452
Reviewed-on: http://review.whamcloud.com/11326


Reviewed-by: wang di <di.wang@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>