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/r8a774b1_beacon_defconfig b/configs/r8a774b1_beacon_defconfig
index 034ed21..0d63e63 100644
--- a/configs/r8a774b1_beacon_defconfig
+++ b/configs/r8a774b1_beacon_defconfig
@@ -9,6 +9,7 @@
 CONFIG_TARGET_BEACON_RZG2N=y
 # CONFIG_SPL is not set
 CONFIG_LTO=y
+CONFIG_SYS_LOAD_ADDR=0x58000000
 CONFIG_FIT=y
 CONFIG_SUPPORT_RAW_INITRD=y
 # CONFIG_ARCH_FIXUP_FDT_MEMORY is not set