dt-bindings: phy: Convert ti,keystone-usbphy to DT schema

Convert the TI Keystone USB PHY binding to DT schema format. Drop the
"#address-cells" and "#size-cells" properties which don't make sense
without any child nodes.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250607212641.744683-1-robh@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: robherring

Documentation/devicetree/bindings/phy/keystone-usb-phy.txt

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/ti,keystone-usbphy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI Keystone USB PHY
+
+maintainers:
+  - Nishanth Menon <nm@ti.com>
+  - Santosh Shilimkar <ssantosh@kernel.org>
+
+description:
+  The main purpose of this PHY driver is to enable the USB PHY reference clock
+  gate on the Keystone SOC for both the USB2 and USB3 PHY. Otherwise it is just
+  an NOP PHY driver. Hence this node is referenced as both the usb2 and usb3
+  phy node in the USB Glue layer driver node.
+
+properties:
+  compatible:
+    const: ti,keystone-usbphy
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    usb-phy@2620738 {
+        compatible = "ti,keystone-usbphy";
+        reg = <0x2620738 32>;
+    };