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/p2571_defconfig b/configs/p2571_defconfig
index 8c3a184..0cf4ddc 100644
--- a/configs/p2571_defconfig
+++ b/configs/p2571_defconfig
@@ -7,6 +7,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="tegra210-p2571"
 CONFIG_TEGRA210=y
 CONFIG_TARGET_P2571=y
+CONFIG_SYS_LOAD_ADDR=0x80080000
 CONFIG_OF_SYSTEM_SETUP=y
 CONFIG_CONSOLE_MUX=y
 CONFIG_SYS_STDIO_DEREGISTER=y