dt-bindings: phy-qcom-ipq4019-usb: add binding document

This patch adds the binding documentation for the HS/SS USB PHY found
inside Qualcom Dakota SoCs.
Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Link: https://lore.kernel.org/r/20200503201823.531757-2-robert.marko@sartura.hrSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/qcom-usb-ipq4019-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/phy/qcom-usb-ipq4019-phy.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Qualcom IPQ40xx Dakota HS/SS USB PHY
+
+maintainers:
+  - Robert Marko <robert.marko@sartura.hr>
+
+properties:
+  compatible:
+    enum:
+      - qcom,usb-ss-ipq4019-phy
+      - qcom,usb-hs-ipq4019-phy
+
+  reg:
+    maxItems: 1
+
+  resets:
+    maxItems: 2
+
+  reset-names:
+    items:
+      - const: por_rst
+      - const: srif_rst
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - resets
+  - reset-names
+  - "#phy-cells"
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-ipq4019.h>
+
+    hsphy@a8000 {
+      #phy-cells = <0>;
+      compatible = "qcom,usb-hs-ipq4019-phy";
+      reg = <0xa8000 0x40>;
+      resets = <&gcc USB2_HSPHY_POR_ARES>,
+               <&gcc USB2_HSPHY_S_ARES>;
+      reset-names = "por_rst", "srif_rst";
+    };