dt-bindings: phy: airoha: Add PCIe PHY controller

Introduce device-tree binding documentation for Airoha EN7581 PCIe PHY
controller.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/656133f865433c1d02f00a3abbb1aa9312d2a24e.1718485860.git.lorenzo@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/airoha,en7581-pcie-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/airoha,en7581-pcie-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Airoha EN7581 PCI-Express PHY
+
+maintainers:
+  - Lorenzo Bianconi <lorenzo@kernel.org>
+
+description:
+  The PCIe PHY supports physical layer functionality for PCIe Gen2/Gen3 port.
+
+properties:
+  compatible:
+    const: airoha,en7581-pcie-phy
+
+  reg:
+    items:
+      - description: PCIE analog base address
+      - description: PCIE lane0 base address
+      - description: PCIE lane1 base address
+
+  reg-names:
+    items:
+      - const: csr-2l
+      - const: pma0
+      - const: pma1
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/phy/phy.h>
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        phy@11e80000 {
+            compatible = "airoha,en7581-pcie-phy";
+            #phy-cells = <0>;
+            reg = <0x0 0x1fa5a000 0x0 0xfff>,
+                  <0x0 0x1fa5b000 0x0 0xfff>,
+                  <0x0 0x1fa5c000 0x0 0xfff>;
+            reg-names = "csr-2l", "pma0", "pma1";
+        };
+    };