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/meesc_defconfig b/configs/meesc_defconfig
index 69d8935..ee486b6 100644
--- a/configs/meesc_defconfig
+++ b/configs/meesc_defconfig
@@ -8,6 +8,7 @@
 CONFIG_ENV_OFFSET=0xC0000
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="at91sam9263ek"
+CONFIG_SYS_LOAD_ADDR=0x20100000
 CONFIG_FIT=y
 CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9263,SYS_USE_NANDFLASH"
 CONFIG_BOOTDELAY=3