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/3c120_defconfig b/configs/3c120_defconfig
index 61a242e..a4b1b92 100644
--- a/configs/3c120_defconfig
+++ b/configs/3c120_defconfig
@@ -5,6 +5,7 @@
 CONFIG_ENV_SECT_SIZE=0x20000
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="3c120_devboard"
+CONFIG_SYS_LOAD_ADDR=0xd4000000
 CONFIG_FIT=y
 # CONFIG_AUTOBOOT is not set
 CONFIG_SYS_CONSOLE_INFO_QUIET=y