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_virt_defconfig b/configs/xilinx_versal_virt_defconfig
index 62e8271..1159862 100644
--- a/configs/xilinx_versal_virt_defconfig
+++ b/configs/xilinx_versal_virt_defconfig
@@ -11,6 +11,7 @@
 CONFIG_DEFINE_TCM_OCM_MMAP=y
 CONFIG_COUNTER_FREQUENCY=100000000
 CONFIG_DISTRO_DEFAULTS=y
+CONFIG_SYS_LOAD_ADDR=0x8000000
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 # CONFIG_ARCH_FIXUP_FDT_MEMORY is not set