unregister_blkdev() delete redundant messages in callers

No need to warn unregister_blkdev() failure by the callers.  (The previous
patch makes unregister_blkdev() print error message in error case)

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index f4f7d35..846614e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -161,9 +161,7 @@
 {
 	kmem_cache_destroy(_tio_cache);
 	kmem_cache_destroy(_io_cache);
-
-	if (unregister_blkdev(_major, _name) < 0)
-		DMERR("unregister_blkdev failed");
+	unregister_blkdev(_major, _name);
 
 	_major = 0;