staging/lustre/mdc: cleanup intent if mdc_finish_enqueue() fails

In mdc_enqueue() clear the lock handle, lock mode, and request stored
in the lookup intent if mdc_finish_enqueue() fails.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/10963
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5289


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