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/sei610_defconfig b/configs/sei610_defconfig
index e11f36a..f10642b 100644
--- a/configs/sei610_defconfig
+++ b/configs/sei610_defconfig
@@ -14,6 +14,7 @@
 CONFIG_IDENT_STRING=" sei610"
 # CONFIG_PSCI_RESET is not set
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_LOAD_ADDR=0x1000000
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_USE_PREBOOT=y
 CONFIG_PREBOOT="run load_logo"