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/dm-log.c b/drivers/md/dm-log.c
index e6b6a9d..67a6f31 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -9,9 +9,9 @@
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/vmalloc.h>
+#include <linux/dm-io.h>
+#include <linux/dm-dirty-log.h>
 
-#include "dm-log.h"
-#include "dm-io.h"
 #include "dm.h"
 
 #define DM_MSG_PREFIX "dirty region log"