dm: publish dm_table_unplug_all

Publish dm_table_unplug_all in include/linux/device-mapper.h because this
function is used by targets.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 6b80961..e462c7f 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -238,6 +238,11 @@
 int dm_table_complete(struct dm_table *t);
 
 /*
+ * Unplug all devices in a table.
+ */
+void dm_table_unplug_all(struct dm_table *t);
+
+/*
  * Table reference counting.
  */
 struct dm_table *dm_get_table(struct mapped_device *md);