devicetree: Allow child-binding bus controller without a need of compatible

[kurddt]

Currently it's not possible to have a child-bindings acting as a bus controller unless there is a compatible property associated to it

Currently to describe an i2c mux one would need to create a binding like the following:

compatible: "ti,tca9546a"
include: "i2c-device.yaml"

properties:
    label:
        required: true
        type: string
        description: tca9546

child-binding:
    include: "i2c-controller.yaml"
    compatible: "ti,tca9546a-child"
    description: Downlink I2C bus tca9546

The child binding is only used as a placeholder and will probably not be used by the device driver but without it the child-binding is not taken as a bus controller

The following should be possible:

compatible: "ti,tca9546a"
include: "i2c-device.yaml"
properties:
    label:
        required: true
        type: string
        description: tca9546

child-binding:
    include: "i2c-controller.yaml"
    description: Downlink I2C bus tca9546

[kurddt]

See #32071

[zephyrbot]

Hi @galak,

This issue, marked as an Enhancement, was opened a while ago and did not get any traction. It was just assigned to you based on the labels. If you don't consider yourself the right person to address this issue, please re-assing it to the right person.

Please take a moment to review if the issue is still relevant to the project. If it is, please provide feedback and direction on how to move forward. If it is not, has already been addressed, is a duplicate, or is no longer relevant, please close it with a short comment explaining the reason.

@kurddt you are also encouraged to help moving this issue forward by providing additional information and confirming this request/issue is still relevant to you.

Thanks!