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/ls1021aqds_nand_defconfig b/configs/ls1021aqds_nand_defconfig
index a7eb20e..6864610 100644
--- a/configs/ls1021aqds_nand_defconfig
+++ b/configs/ls1021aqds_nand_defconfig
@@ -19,6 +19,7 @@
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
 CONFIG_AHCI=y
+CONFIG_SYS_LOAD_ADDR=0x82000000
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_OF_BOARD_SETUP=y