mtd: nand: Add missing copyright information

Some drivers have been derived from others which have then been removed
from the source tree. When this is the case, add mention the copyright
of the source file(s) they've been derived from.
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

drivers/mtd/nand/ams-delta.c

@@ -2,6 +2,9 @@
  *  Copyright (C) 2006 Jonathan McDowell <noodles@earth.li>
  *
  *  Derived from drivers/mtd/nand/toto.c (removed in v2.6.28)
+ *    Copyright (c) 2003 Texas Instruments
+ *    Copyright (c) 2002 Thomas Gleixner <tgxl@linutronix.de>
+ *
  *  Converted to platform driver by Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
  *  Partially stolen from plat_nand.c
  *

drivers/mtd/nand/fsmc_nand.c

@@ -8,6 +8,8 @@
  * Ashish Priyadarshi
  *
  * Based on drivers/mtd/nand/nomadik_nand.c (removed in v3.8)
+ *  Copyright © 2007 STMicroelectronics Pvt. Ltd.
+ *  Copyright © 2009 Alessandro Rubini
  *
  * This file is licensed under the terms of the GNU General Public
  * License version 2. This program is licensed "as is" without any