drivers/base/core.c: Remove two unused variables and two useless calls to kfree

old_class_name, and new_class_name are never used. This patch remove the
declaration and calls to kfree.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@r1 forall@
type T; identifier i;
@@
* T *i = NULL;
  ... when != i
* kfree(i);
// </smpl>
Signed-off-by: Peter Senna Tschudin <peter.senna@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/core.c

@@ -1685,8 +1685,6 @@ EXPORT_SYMBOL_GPL(device_destroy);
  */
 int device_rename(struct device *dev, const char *new_name)
 {
-	char *old_class_name = NULL;
-	char *new_class_name = NULL;
 	char *old_device_name = NULL;
 	int error;
 
@@ -1717,8 +1715,6 @@ int device_rename(struct device *dev, const char *new_name)
 out:
 	put_device(dev);
 
-	kfree(new_class_name);
-	kfree(old_class_name);
 	kfree(old_device_name);
 
 	return error;