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/smdkv310_defconfig b/configs/smdkv310_defconfig
index ac84fde..2786002 100644
--- a/configs/smdkv310_defconfig
+++ b/configs/smdkv310_defconfig
@@ -10,6 +10,7 @@
 CONFIG_SPL=y
 CONFIG_IDENT_STRING=" for SMDKC210/V310"
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x43e00000
 # CONFIG_USE_BOOTCOMMAND is not set
 # CONFIG_SPL_FRAMEWORK is not set
 CONFIG_SYS_PROMPT="SMDKV310 # "