xilinx: Add support for ENV_VARS_UBOOT_RUNTIME_CONFIG

Start to use ENV_VARS_UBOOT_RUNTIME_CONFIG to enable/disable updating
variables with run time information.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/versal/board.c b/board/xilinx/versal/board.c
index 3dc7044..a5ca4ca 100644
--- a/board/xilinx/versal/board.c
+++ b/board/xilinx/versal/board.c
@@ -116,6 +116,9 @@
 		return 0;
 	}
 
+	if (!CONFIG_IS_ENABLED(ENV_VARS_UBOOT_RUNTIME_CONFIG))
+		return 0;
+
 	bootmode = versal_get_bootmode();
 
 	puts("Bootmode: ");