dm thin: correct module description

Remove duplicate copy of string "device-mapper" (DM_NAME) from
MODULE_DESCRIPTION.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 69a2d51..2fd87b5 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2767,6 +2767,6 @@
 module_init(dm_thin_init);
 module_exit(dm_thin_exit);
 
-MODULE_DESCRIPTION(DM_NAME "device-mapper thin provisioning target");
+MODULE_DESCRIPTION(DM_NAME " thin provisioning target");
 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
 MODULE_LICENSE("GPL");