Convert CONFIG_SYS_SPI_U_BOOT_OFFS to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_SPI_U_BOOT_OFFS

Signed-off-by: Hannes Schmelzer <hannes.schmelzer@br-automation.com>
[trini: Expose this for SPL_SPI_SUNXI for now]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 660aa66..94dcdff 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -1002,6 +1002,14 @@
 
 endif # SPL_SPI_FLASH_SUPPORT
 
+config SYS_SPI_U_BOOT_OFFS
+	hex "address of u-boot payload in SPI flash"
+	default 0x0
+	depends on SPL_SPI_LOAD || SPL_SPI_SUNXI
+	help
+	 Address within SPI-Flash from where the u-boot payload is fetched
+	 from.
+
 config SPL_SPI_SUPPORT
 	bool "Support SPI drivers"
 	help