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/ls1021aiot_qspi_defconfig b/configs/ls1021aiot_qspi_defconfig
index c155689..5e2d725 100644
--- a/configs/ls1021aiot_qspi_defconfig
+++ b/configs/ls1021aiot_qspi_defconfig
@@ -11,6 +11,7 @@
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="ls1021a-iot-duart"
 CONFIG_AHCI=y
+CONFIG_SYS_LOAD_ADDR=0x82000000
 CONFIG_SYS_EXTRA_OPTIONS="QSPI_BOOT"
 CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_MISC_INIT_R=y