overlay_mgr

Required properties:
- compatible: "linux,overlay_manager";

Optional properties:
- starts from the word "hardware": hardware_cfg_0

These properties can be chosen from kernel command line:
overlay_mgr.overlay_dt_entry=hardware_cfg_0
DT contains main overlay_mng entry with all possible
HW config setups. And then kernel command line option
will allow to choose between them.

Example:
    overlay_mgr {
        compatible = "linux,overlay_manager";
        hardware_cfg_0 {
            overlay@0 {
                    fragment@0 {
                            __overlay__ {
                            };
                    };
            };
            overlay@1 {
                    fragment@0 {
                            __overlay__ {
                            };
                    };
            };
        };
    };
