drivers/md: change module.h -> export.h in persistent-data/dm-*

For the files which are not themselves modular, we can change
them to include only the smaller export.h since all they are
doing is looking for EXPORT_SYMBOL.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/md/persistent-data/dm-btree-remove.c

@@ -8,7 +8,7 @@
 #include "dm-btree-internal.h"
 #include "dm-transaction-manager.h"
 
-#include <linux/module.h>
+#include <linux/export.h>
 
 /*
  * Removing an entry from a btree

drivers/md/persistent-data/dm-btree.c

@@ -8,7 +8,7 @@
 #include "dm-space-map.h"
 #include "dm-transaction-manager.h"
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/device-mapper.h>
 
 #define DM_MSG_PREFIX "btree"

drivers/md/persistent-data/dm-space-map-disk.c

@@ -12,7 +12,7 @@
 
 #include <linux/list.h>
 #include <linux/slab.h>
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/device-mapper.h>
 
 #define DM_MSG_PREFIX "space map disk"

drivers/md/persistent-data/dm-transaction-manager.c

@@ -10,7 +10,7 @@
 #include "dm-space-map-metadata.h"
 #include "dm-persistent-data-internal.h"
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/device-mapper.h>