dm: move include files

Publish the dm-io, dm-log and dm-kcopyd headers in include/linux.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index be4b069..7be09ee 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -3,7 +3,7 @@
 #
 
 dm-mod-objs	:= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
-		   dm-ioctl.o dm-io.o kcopyd.o
+		   dm-ioctl.o dm-io.o dm-kcopyd.o
 dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o
 dm-snapshot-objs := dm-snap.o dm-exception-store.o
 dm-mirror-objs	:= dm-raid1.o