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/synquacer_developerbox_defconfig b/configs/synquacer_developerbox_defconfig
index 13736a4..510e44a 100644
--- a/configs/synquacer_developerbox_defconfig
+++ b/configs/synquacer_developerbox_defconfig
@@ -9,6 +9,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="synquacer-sc2a11-developerbox"
 CONFIG_TARGET_DEVELOPERBOX=y
 CONFIG_AHCI=y
+CONFIG_SYS_LOAD_ADDR=0x80000000
 CONFIG_FIT=y
 CONFIG_BOOTSTAGE_STASH_SIZE=4096
 CONFIG_HUSH_PARSER=y