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/vinco_defconfig b/configs/vinco_defconfig
index 07fb27f..17f6256 100644
--- a/configs/vinco_defconfig
+++ b/configs/vinco_defconfig
@@ -9,6 +9,7 @@
 CONFIG_ENV_SECT_SIZE=0x1000
 CONFIG_DEFAULT_DEVICE_TREE="at91-vinco"
 CONFIG_ENV_VARS_UBOOT_CONFIG=y
+CONFIG_SYS_LOAD_ADDR=0x22000000
 CONFIG_SPI_BOOT=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y