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/nsim_hs38_defconfig b/configs/nsim_hs38_defconfig
index cdbcba1..eea3702 100644
--- a/configs/nsim_hs38_defconfig
+++ b/configs/nsim_hs38_defconfig
@@ -8,6 +8,7 @@
 CONFIG_DEBUG_UART_CLOCK=70000000
 CONFIG_SYS_CLK_FREQ=70000000
 CONFIG_DEBUG_UART=y
+CONFIG_SYS_LOAD_ADDR=0x82000000
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200n8"