dt-bindings: usb: qcom,dwc3: Validate DWC3 sub-node

Qualcomm msm8996/sc7180/sdm845 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
Qualcomm 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>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201210090944.16283-19-Sergey.Semin@baikalelectronics.ruSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/qcom,dwc3.yaml

@@ -103,11 +103,8 @@ 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
@@ -162,7 +159,7 @@ examples:
 
             resets = <&gcc GCC_USB30_PRIM_BCR>;
 
-            dwc3@a600000 {
+            usb@a600000 {
                 compatible = "snps,dwc3";
                 reg = <0 0x0a600000 0 0xcd00>;
                 interrupts = <GIC_SPI 133 IRQ_TYPE_LEVEL_HIGH>;