LU-5261 osc: use wait_for_completion_killable() instead

LU-5261 osc: use wait_for_completion_killable() instead

Use wait_for_completion_killable() instead of wait_for_completion()
so that the user process can be killed if there is a problem on the
OST.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: Ia3ed5cb981755483bd2f4c3f2cb4cc90c3ca5207
Reviewed-on: http://review.whamcloud.com/11021
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>