devicetree: allow generation of properties that don't have a binding

[galak]

Today we only generate defines if there is a binding that matches the node. The matching of binding to a node is done via compatible.

There are a number of cases related to nodes that describe memory regions that don't have a compatible and thus dont have bindings. Its completely feasible with the new generation and macro scheme to access such data.

For example we might have:

chosen {
    zephyr,ipc_shm = &shmem;
}

reserved-memory {
    #address-cells = <1>;
    #size-cells = <1>;
   ranges;
   shem: shem@f000 {
       reg = <0f000 0x1000>;
   };

Today this will not work properly as we'll not have any reg properties generated for the smem@f000 node.

[galak]

There are also a number of cases in which we incorrectly mark memory nodes as mmio-sram compatible that are not.

[galak]

We merged a change that allows generation for a known fixed set of properties as defined by the DTS spec.