staging/lustre/llite: correct request handling after ll_lookup_it()

In the FIFO cases of ll_atomic_open() and ll_lookup_nd() remove
spurious calls to ptlrpc_req_finished(). Explain that these cases are
unreachable in practice anyway.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/17068
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-7402


Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>