dt-bindings: usb: intel, keembay-dwc3: Validate DWC3 sub-node

Intel Keem Bay DWC3 compatible DT nodes are supposed to have a DWC USB3
compatible sub-node to describe a fully functioning USB interface. Let's
use the available DWC USB3 DT schema to validate the Intel Keem Bay DWC3
sub-nodes.

Note since the generic DWC USB3 DT node is supposed to be named as generic
USB HCD ("^usb(@.*)?") one we have to accordingly fix the sub-nodes name
regexp and fix the DT node example.

Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-20-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/intel,keembay-dwc3.yaml

@@ -34,11 +34,8 @@ properties:
 # Required child node:
 
 patternProperties:
-  "^dwc3@[0-9a-f]+$":
-    type: object
-    description:
-      A child node must exist to represent the core DWC3 IP block.
-      The content of the node is defined in dwc3.txt.
+  "^usb@[0-9a-f]+$":
+    $ref: snps,dwc3.yaml#
 
 required:
   - compatible
@@ -68,7 +65,7 @@ examples:
           #address-cells = <1>;
           #size-cells = <1>;
 
-          dwc3@34000000 {
+          usb@34000000 {
                 compatible = "snps,dwc3";
                 reg = <0x34000000 0x10000>;
                 interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>;