stop passing nameidata to ->lookup()

Just the flags; only NFS cares even about that, but there are
legitimate uses for such argument.  And getting rid of that
completely would require splitting ->lookup() into a couple
of methods (at least), so let's leave that alone for now...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 56750b7..690f573 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -434,5 +434,5 @@
 
 --
 [mandatory]
-	The witch is dead!  Well, 1/3 of it, anyway.  ->d_revalidate() does *not*
-take struct nameidata anymore; just the flags.
+	The witch is dead!  Well, 2/3 of it, anyway.  ->d_revalidate() and
+->lookup() do *not* take struct nameidata anymore; just the flags.