dt-bindings: usb: xhci: Add support for BCM2711

The xHCI IP on the BCM2711 SoC is compatible to "brcm,xhci-brcm-v2",
but also requires a power domain. So introduce a new compatible
and the specific constraints. Since the key allOf can only occur
once, merge the reference below.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20231205200531.8232-2-wahrenst@gmx.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -9,9 +9,6 @@ title: USB xHCI Controller
 maintainers:
   - Mathias Nyman <mathias.nyman@intel.com>
 
-allOf:
-  - $ref: usb-xhci.yaml#
-
 properties:
   compatible:
     oneOf:
@@ -25,6 +22,11 @@ properties:
               - marvell,armada-380-xhci
               - marvell,armada-8k-xhci
           - const: generic-xhci
+      - description: Broadcom SoCs with power domains
+        items:
+          - enum:
+              - brcm,bcm2711-xhci
+          - const: brcm,xhci-brcm-v2
       - description: Broadcom STB SoCs with xHCI
         enum:
           - brcm,xhci-brcm-v2
@@ -49,6 +51,9 @@ properties:
       - const: core
       - const: reg
 
+  power-domains:
+    maxItems: 1
+
 unevaluatedProperties: false
 
 required:
@@ -56,6 +61,20 @@ required:
   - reg
   - interrupts
 
+allOf:
+  - $ref: usb-xhci.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: brcm,bcm2711-xhci
+    then:
+      required:
+        - power-domains
+    else:
+      properties:
+        power-domains: false
+
 examples:
   - |
     usb@f0931000 {