sunxi/nand: Add support to the SPL for loading u-boot from internal NAND memory

This commit adds support to the sunxi SPL to load u-boot from the internal
NAND. Note this only adds support to access the boot partitions to load
u-boot, full NAND support to load the kernel, etc. from the nand data
partition will come later.

Signed-off-by: Roy Spliet <r.spliet@ultimaker.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 6f5fde9..c6c876d 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -271,6 +271,18 @@
 	slot or emmc on mmc1 - mmc3. Setting this to 1, 2 or 3 will enable
 	support for this.
 
+config SPL_NAND_SUPPORT
+	bool "SPL/NAND mode support"
+	depends on SPL
+	default n
+	---help---
+	  This enables support for booting from NAND internal
+	  memory. U-Boot SPL doesn't detect where is it load from,
+	  therefore this option is needed to properly load image from
+	  flash. Option also disables MMC functionality on U-Boot due to
+	  initialization errors encountered, when both controllers are
+	  enabled.
+
 config USB0_VBUS_PIN
 	string "Vbus enable pin for usb0 (otg)"
 	default ""