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/xilinx_versal_mini_defconfig b/configs/xilinx_versal_mini_defconfig
index 7f75f9b..1dbed04 100644
--- a/configs/xilinx_versal_mini_defconfig
+++ b/configs/xilinx_versal_mini_defconfig
@@ -13,6 +13,7 @@
 CONFIG_COUNTER_FREQUENCY=100000000
 # CONFIG_PSCI_RESET is not set
 # CONFIG_EXPERT is not set
+CONFIG_SYS_LOAD_ADDR=0x8000000
 # CONFIG_LEGACY_IMAGE_FORMAT is not set
 # CONFIG_AUTOBOOT is not set
 CONFIG_SYS_CONSOLE_INFO_QUIET=y