LU-2845 osp: fix osp precreate thread init error handling

LU-2845 osp: fix osp precreate thread init error handling

If osp device hasn't connected OST, osp_precreate_thread() should
heed to that and bypass the normal quitting path.

Signed-off-by: Bobi Jam <bobijam.xu@intel.com>
Change-Id: I27d18dfd4d7d55c97eeb169b5d7dc7042a42fd33
Reviewed-on: http://review.whamcloud.com/5508
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>