[CMD][FDT_OVERLAY] Remove warn-message if no node is found

This is no error but may be the normal case on some platforms.

cmd/seco_fdt_overlay.c

@@ -305,7 +305,6 @@ static int find_devconf_node(void)
 	// Find subnode named 'overlays' 
 	node_offset = fdt_find_node(node_offset, NAME, "overlays", true);
 	if( node_offset < 0){
-		puts("Failed to find overlay in 'seco,devconf' node.\n");
 		return -1;
 	}