mtd: nand: Make CONFIG_SYS_NAND_U_BOOT_OFFS configurable through Kconfig

Make CONFIG_SYS_NAND_U_BOOT_OFFS configurable through Kconfig, just like
SYS_NAND_BUSWIDTH_16BIT this is only enabled on some SoCs using depends,
to avoid double defining it for SoCs which have not yet moved to Kconfig
for this.

Having this in Kconfig is useful because this is something which may
differ from one board to the other even when using the same SoC.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
Acked-by: Scott Wood <scottwood@freescale.com>

drivers/mtd/nand/Kconfig

@@ -92,6 +92,15 @@ config SYS_NAND_BUSWIDTH_16BIT
 	    not available while configuring controller. So a static CONFIG_NAND_xx
 	    is needed to know the device's bus-width in advance.
 
+# Enhance depends when converting drivers to Kconfig which use this config
+config SYS_NAND_U_BOOT_OFFS
+	hex "Location in NAND to read U-Boot from"
+	default 0x8000 if NAND_SUNXI
+	depends on NAND_SUNXI
+	help
+	Set the offset from the start of the nand where u-boot should be
+	loaded from.
+
 if SPL
 
 config SPL_NAND_DENALI

include/configs/sunxi-common.h

@@ -139,7 +139,6 @@
 
 #ifdef CONFIG_NAND_SUNXI
 #define CONFIG_SPL_NAND_SUPPORT 1
-#define CONFIG_SYS_NAND_U_BOOT_OFFS 0x008000
 #endif
 
 /* mmc config */