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/mx53cx9020_defconfig b/configs/mx53cx9020_defconfig
index 8ee442f..6a18f83 100644
--- a/configs/mx53cx9020_defconfig
+++ b/configs/mx53cx9020_defconfig
@@ -9,6 +9,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="imx53-cx9020"
 # CONFIG_CMD_BMODE is not set
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x70010000
 CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/beckhoff/mx53cx9020/imximage.cfg"
 CONFIG_BOOTDELAY=1
 CONFIG_USE_PREBOOT=y