dt-bindings: usb: generic-ehci: allow usb-hcd schema properties

Allow properties and usb-device child nodes as defined in usb-hcd.yaml, by
using unevaluatedProperties: false. By the way, remove the "companion"
property as it's redundant with usb-hcd.yaml.
As example, this allows an onboard hub, to be described in generic-ehci
controller node:
usb {
compatible = "generic-ehci";
#address-cells = <1>;
#size-cells = <0>;
/* onboard HUB */
hub@1 {
compatible = "usb424,2514";
reg = <1>;
vdd-supply = <&v3v3>;
};
};

Without this, dtbs_check complains on '#address-cells', '#size-cells',
'hub@1' do not match any of the regexes: 'pinctrl-[0-9]+'
From schema: ..../generic-ehci.yaml

Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Fabrice Gasnier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/usb/generic-ehci.yaml

···
       Set this flag to indicate that the hardware sometimes turns on
       the OC bit when an over-current isn't actually present.
 
-  companion:
-    $ref: /schemas/types.yaml#/definitions/phandle
-    description:
-      Phandle of a companion.
-
   phys:
     minItems: 1
     maxItems: 3
···
   - reg
   - interrupts
 
-additionalProperties: false
+unevaluatedProperties: false
 
 examples:
   - |