dt-bindings: usb: Convert USB HCD generic binding to YAML

The USB HCD generic binding is used by many USB host bindings.

In order to allow the DT validation to happen on those, let's create a YAML
description for that generic binding that can be referenced later on.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/usb-hcd.txt

-Generic USB HCD (Host Controller Device) Properties
-
-Optional properties:
-- phys: a list of all USB PHYs on this HCD
-
-Example:
-	&usb1 {
-		phys = <&usb2_phy1>, <&usb3_phy1>;
-	};

Documentation/devicetree/bindings/usb/usb-hcd.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/usb-hcd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic USB Host Controller Device Tree Bindings
+
+maintainers:
+  - Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+properties:
+  $nodename:
+    pattern: "^usb(@.*)?"
+
+  phys:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description:
+      List of all the USB PHYs on this HCD
+
+examples:
+  - |
+    usb {
+        phys = <&usb2_phy1>, <&usb3_phy1>;
+    };