genhd.c reference in Documentation/kobjects.txt

block/genhd.c no longer in drivers/.  Update Documentation/kobjects.txt
Signed-off-by: Brandon Philips <brandon@ifup.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/kobject.txt

@@ -247,7 +247,7 @@ the object-specific fields, which include:
 - default_attrs: Default attributes to be exported via sysfs when the
   object is registered.Note that the last attribute has to be
   initialized to NULL ! You can find a complete implementation
-  in drivers/block/genhd.c
+  in block/genhd.c
 
 
 Instances of struct kobj_type are not registered; only referenced by