switch d_materialise_unique() users to d_splice_alias()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 0f3a139..b6b55a9 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -463,3 +463,7 @@
 	of the in-tree instances did).  inode_hash_lock is still held,
 	of course, so they are still serialized wrt removal from inode hash,
 	as well as wrt set() callback of iget5_locked().
+--
+[mandatory]
+	d_materialise_unique() is gone; d_splice_alias() does everything you
+	need now.  Remember that they have opposite orders of arguments ;-/