kobj: kref.h incorrectly describes itself as kref.c.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

include/linux/kref.h

 /*
- * kref.c - library routines for handling generic reference counted objects
+ * kref.h - library routines for handling generic reference counted objects
  *
  * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
  * Copyright (C) 2004 IBM Corp.