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/elgin-rv1108_defconfig b/configs/elgin-rv1108_defconfig
index af4f3f1..1728044 100644
--- a/configs/elgin-rv1108_defconfig
+++ b/configs/elgin-rv1108_defconfig
@@ -10,6 +10,7 @@
 CONFIG_DEBUG_UART_BASE=0x10210000
 CONFIG_DEBUG_UART_CLOCK=24000000
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_LOAD_ADDR=0x62000000
 # CONFIG_USE_BOOTCOMMAND is not set
 CONFIG_DEFAULT_FDT_FILE="rv1108-elgin-r1.dtb"
 # CONFIG_DISPLAY_CPUINFO is not set