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/ventana_defconfig b/configs/ventana_defconfig
index d628840..4472f96 100644
--- a/configs/ventana_defconfig
+++ b/configs/ventana_defconfig
@@ -8,6 +8,7 @@
 CONFIG_SPL_TEXT_BASE=0x00108000
 CONFIG_TEGRA20=y
 CONFIG_TARGET_VENTANA=y
+CONFIG_SYS_LOAD_ADDR=0x1000000
 CONFIG_OF_SYSTEM_SETUP=y
 CONFIG_USE_PREBOOT=y
 CONFIG_SYS_PROMPT="Tegra20 (Ventana) # "