arm64: a8k: dts: Add support for NAND devices on A8K platform

Add NAND to CP master device tree. Add armada-7040-db-nand
device tree for the board configured with NAND boot device.
Add comment about boot device ID to armada-7040-db DTS.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
Cc: Stefan Roese <sr@denx.de>
Cc: Igal Liberman <igall@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/armada-7040-db.dts b/arch/arm/dts/armada-7040-db.dts
index 84e0dbd..c1a0f46 100644
--- a/arch/arm/dts/armada-7040-db.dts
+++ b/arch/arm/dts/armada-7040-db.dts
@@ -42,6 +42,7 @@
 
 /*
  * Device Tree file for Marvell Armada 7040 Development board platform
+ * Boot device: SPI NOR, 0x32 (SW3)
  */
 
 #include "armada-7040.dtsi"