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/blanche_defconfig b/configs/blanche_defconfig
index eb1dd71..2647f6e 100644
--- a/configs/blanche_defconfig
+++ b/configs/blanche_defconfig
@@ -13,6 +13,7 @@
 CONFIG_ARCH_RMOBILE_BOARD_STRING="Blanche"
 CONFIG_R8A7792=y
 CONFIG_TARGET_BLANCHE=y
+CONFIG_SYS_LOAD_ADDR=0x50000000
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 CONFIG_HUSH_PARSER=y