dm kcopyd: clean interface

Clean up the kcopyd interface to prepare for publishing it in include/linux.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

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

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

diff --cc drivers/md/dm-snap.h
Simple merge

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

diff --cc drivers/md/kcopyd.h
Simple merge