LU-4985 kernel: Store kthread_run result in task_struct ptr

LU-4985 kernel: Store kthread_run result in task_struct ptr

The fix for LU-3498 changed most invocations of kthread_run to store
the result in a variable of task_struct pointer type and check whether
kthread_run returned an error using IS_ERR.  This change updates the
remaining calls to kthread_run to do this as well for consistency.

Signed-off-by: Ryan Haasken <haasken@cray.com>
Change-Id: I18edab018080ec51e9979164234e5bcd02a04f88
Reviewed-on: http://review.whamcloud.com/10266
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>