LU-6578 statahead: drop support for remote entry

LU-6578 statahead: drop support for remote entry

This patch dropped support for remote entry statahead, because it
needs 2 async RPCs to fetch both LOOKUP lock from parent MDT and
UPDATE lock from client MDT, which is complicated. And not
supporting remote entry statahead won't cause any issue.

* pack child fid in statahead request.
* lmv_intent_getattr_async() will compare parent and child MDT,
  if child is remote, return -ENOTSUPP.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: I8c075bab0a716f194eac3c338ffbdd37f787eff6
Reviewed-on: http://review.whamcloud.com/15767
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>