mtd: nand: Add mvebu (PXA / AXP / A38x) NAND device driver

Cloned from the Linux driver v4.2.0-rc2. Plus some patches from
Antoine Tenart enabling controller initialization and ONFI timing
support:

http://lists.infradead.org/pipermail/linux-mtd/2015-July/060197.html

Please note that this driver needs the Linux NAND subsystem sync to v4.1
from Scott to be applied:

https://www.mail-archive.com/u-boot@lists.denx.de/msg175762.html

Otherwise it will not compile.

Tested on the Marvell Armada XP DB-MV784MP-GP eval board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Antoine Tenart <antoine.tenart@free-electrons.com>
Cc: Ezeguil Garcia <ezequiel.garcia@free-electrons.com>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Scott Wood <scottwood@freescale.com>
diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 41ebfea..b6dfb0e 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -56,6 +56,13 @@
 
 endchoice
 
+config NAND_PXA3XX
+	bool "Support for NAND on PXA3xx and Armada 370/XP/38x"
+	select SYS_NAND_SELF_INIT
+	help
+	  This enables the driver for the NAND flash device found on
+	  PXA3xx processors (NFCv1) and also on Armada 370/XP (NFCv2).
+
 comment "Generic NAND options"
 
 # Enhance depends when converting drivers to Kconfig which use this config