dt-bindings: phy: Add binding for marvell,mmp3-hsic-phy

This is the PHY chip for USB HSIC on MMP3 platform.

Link: https://lore.kernel.org/r/20191220065314.237624-4-lkundrak@v3.skSigned-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/phy/marvell,mmp3-hsic-phy.yaml

+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright 2019 Lubomir Rintel <lkundrak@v3.sk>
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/phy/marvell,mmp3-hsic-phy.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Marvell MMP3 HSIC PHY
+
+maintainers:
+  - Lubomir Rintel <lkundrak@v3.sk>
+
+properties:
+  compatible:
+    const: marvell,mmp3-hsic-phy
+
+  reg:
+    maxItems: 1
+    description: base address of the device
+
+  reset-gpios:
+    maxItems: 1
+    description: GPIO connected to reset
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - reset-gpios
+  - "#phy-cells"
+
+examples:
+  - |
+    hsic-phy@f0001800 {
+            compatible = "marvell,mmp3-hsic-phy";
+            reg = <0xf0001800 0x40>;
+            reset-gpios = <&gpio 63 GPIO_ACTIVE_HIGH>;
+            #phy-cells = <0>;
+    };