LU-12678 o2iblnd: use need_resched()

LU-12678 o2iblnd: use need_resched()

Rather than using a counter to decide when to drop
the lock and see if we need to reshedule we can
use need_resched(), which is a precise test instead of a guess.

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I43a1d9d0963622953761f25e13bc4781c2b02be2
Reviewed-on: https://review.whamcloud.com/39125
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>