LU-10297 lod: prepare inuse array always

The OST inuse array should be prepared for composite files and for
plain files as well, since creating OST objects in both cases needs
to use it.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: Ibb37b680c68f8883650cdee6bebebc1c4d844623
Reviewed-on: https://review.whamcloud.com/30334
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>