Convert CONFIG_SYS_LOAD_ADDR to Kconfig

Now that we have consistent usage, migrate this symbol to Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/configs/zynq_cse_nand_defconfig b/configs/zynq_cse_nand_defconfig
index 2386da7..7bfca77 100644
--- a/configs/zynq_cse_nand_defconfig
+++ b/configs/zynq_cse_nand_defconfig
@@ -11,6 +11,7 @@
 CONFIG_SPL=y
 CONFIG_SYS_CUSTOM_LDSCRIPT=y
 CONFIG_SYS_LDSCRIPT="arch/arm/mach-zynq/u-boot.lds"
+CONFIG_SYS_LOAD_ADDR=0x0
 # CONFIG_AUTOBOOT is not set
 CONFIG_USE_PREBOOT=y
 # CONFIG_DISPLAY_CPUINFO is not set