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/mscc_servalt_defconfig b/configs/mscc_servalt_defconfig
index 0e98252..c8a9846 100644
--- a/configs/mscc_servalt_defconfig
+++ b/configs/mscc_servalt_defconfig
@@ -12,6 +12,7 @@
 CONFIG_ARCH_MSCC=y
 CONFIG_SOC_SERVALT=y
 CONFIG_SYS_LITTLE_ENDIAN=y
+CONFIG_SYS_LOAD_ADDR=0x100000
 CONFIG_FIT=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y