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/phycore-rk3288_defconfig b/configs/phycore-rk3288_defconfig
index 8ee99e5..2452205 100644
--- a/configs/phycore-rk3288_defconfig
+++ b/configs/phycore-rk3288_defconfig
@@ -12,6 +12,7 @@
 CONFIG_DEBUG_UART_BASE=0xff690000
 CONFIG_DEBUG_UART_CLOCK=24000000
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_LOAD_ADDR=0x800800
 # CONFIG_ANDROID_BOOT_IMAGE is not set
 CONFIG_USE_PREBOOT=y
 CONFIG_DEFAULT_FDT_FILE="rk3288-phycore-rdk.dtb"