LU-3186 lmv: do not need allocate FID for open by FID

LU-3186 lmv: do not need allocate FID for open by FID

We do not need allocate FID or set op_fid2 if it is for
Open by FID, otherwise, it will cause the MDT to open
the file with new FID.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I67e5a52c643228a6d8bd0190ca1a78b047fd1e7a
Reviewed-on: http://review.whamcloud.com/6099
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>