tomoyo: stop including hell knows what

tomoyo/realpath.c needs exactly one include - that of common.h.  It pulls
everything the thing needs, without doing ridiculous garbage such as trying
to include ../../fs/internal.h.  If that alone doesn't scream "layering
violation", I don't know what does; and these days it's all for nothing,
since it fortunately does not use any symbols defined in there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

security/tomoyo/realpath.c

@@ -4,15 +4,7 @@
  * Copyright (C) 2005-2011  NTT DATA CORPORATION
  */
 
-#include <linux/types.h>
-#include <linux/mount.h>
-#include <linux/mnt_namespace.h>
-#include <linux/fs_struct.h>
-#include <linux/magic.h>
-#include <linux/slab.h>
-#include <net/sock.h>
 #include "common.h"
-#include "../../fs/internal.h"
 
 /**
  * tomoyo_encode2 - Encode binary string to ascii string.