dm: convert workqueues to alloc_ordered

Convert all create[_singlethread]_work() users to the new
alloc[_ordered]_workqueue().  This conversion is mechanical and
doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --cc drivers/md/dm-delay.c
Simple merge

diff --cc drivers/md/dm-kcopyd.c
Simple merge

diff --cc drivers/md/dm-mpath.c
Simple merge

diff --cc drivers/md/dm-raid1.c
Simple merge

diff --cc drivers/md/dm-snap-persistent.c
Simple merge

diff --cc drivers/md/dm.c
Simple merge