dt-bindings: phy: mediatek: Add YAML schema for PCIe PHY

Add YAML schema documentation for PCIe PHY on MediaTek chipsets.
Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220617070246.20142-2-jianjun.wang@mediatek.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/mediatek,pcie-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/mediatek,pcie-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek PCIe PHY
+
+maintainers:
+  - Jianjun Wang <jianjun.wang@mediatek.com>
+
+description: |
+  The PCIe PHY supports physical layer functionality for PCIe Gen3 port.
+
+properties:
+  compatible:
+    const: mediatek,mt8195-pcie-phy
+
+  reg:
+    maxItems: 1
+
+  reg-names:
+    items:
+      - const: sif
+
+  "#phy-cells":
+    const: 0
+
+  nvmem-cells:
+    maxItems: 7
+    description:
+      Phandles to nvmem cell that contains the efuse data, if unspecified,
+      default value is used.
+
+  nvmem-cell-names:
+    items:
+      - const: glb_intr
+      - const: tx_ln0_pmos
+      - const: tx_ln0_nmos
+      - const: rx_ln0
+      - const: tx_ln1_pmos
+      - const: tx_ln1_nmos
+      - const: rx_ln1
+
+  power-domains:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    phy@11e80000 {
+        compatible = "mediatek,mt8195-pcie-phy";
+        #phy-cells = <0>;
+        reg = <0x11e80000 0x10000>;
+        reg-names = "sif";
+        nvmem-cells = <&pciephy_glb_intr>,
+                      <&pciephy_tx_ln0_pmos>,
+                      <&pciephy_tx_ln0_nmos>,
+                      <&pciephy_rx_ln0>,
+                      <&pciephy_tx_ln1_pmos>,
+                      <&pciephy_tx_ln1_nmos>,
+                      <&pciephy_rx_ln1>;
+        nvmem-cell-names = "glb_intr", "tx_ln0_pmos",
+                           "tx_ln0_nmos", "rx_ln0",
+                           "tx_ln1_pmos", "tx_ln1_nmos",
+                           "rx_ln1";
+        power-domains = <&spm 2>;
+    };