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/adp-ag101p_defconfig b/configs/adp-ag101p_defconfig
index 3e898e5..3e53639 100644
--- a/configs/adp-ag101p_defconfig
+++ b/configs/adp-ag101p_defconfig
@@ -5,6 +5,7 @@
 CONFIG_ENV_SECT_SIZE=0x20000
 CONFIG_DEFAULT_DEVICE_TREE="ag101p"
 CONFIG_TARGET_ADP_AG101P=y
+CONFIG_SYS_LOAD_ADDR=0x300000
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 # CONFIG_AUTO_COMPLETE is not set