LU-10761 osd-ldiskfs: not create REMOTE_PARENT_DIR on OST

LU-10761 osd-ldiskfs: not create REMOTE_PARENT_DIR on OST

The REMOTE_PARENT_DIR is used to link remote object which parent
resides on remote MDT to the global namespace. It is only useful
for MDT. So it is unnecessary to create such directory on OST.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I240de3f69cde04740cb7f71ebaf9048407a900dc
Reviewed-on: https://review.whamcloud.com/31508
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>