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/s5p4418_nanopi2_defconfig b/configs/s5p4418_nanopi2_defconfig
index d99c30b..858f2ae 100644
--- a/configs/s5p4418_nanopi2_defconfig
+++ b/configs/s5p4418_nanopi2_defconfig
@@ -14,6 +14,7 @@
 CONFIG_ROOT_DEV=1
 CONFIG_BOOT_PART=1
 CONFIG_ROOT_PART=2
+CONFIG_SYS_LOAD_ADDR=0x71080000
 CONFIG_FIT=y
 CONFIG_FIT_BEST_MATCH=y
 CONFIG_SUPPORT_RAW_INITRD=y