dt-bindings: phy: Convert Northstar 2 PCIe PHY to YAML

Convert the Broadcom Northstar 2 PCIe PHY Device Tree binding to YAML
and rename it accordingly in the process since it had nothing to do with
a MDIO mux on the PCI(e) bus. This is a pre-requisite to updating
another binding file to YAML.

Signed-off-by: Florian Fainelli <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

Documentation/devicetree/bindings/phy/brcm,mdio-mux-bus-pci.txt

···
-* Broadcom NS2 PCIe PHY binding document
-
-Required bus properties:
-- reg: MDIO Bus number for the MDIO interface
-- #address-cells: must be 1
-- #size-cells: must be 0
-
-Required PHY properties:
-- compatible: should be "brcm,ns2-pcie-phy"
-- reg: MDIO Phy ID for the MDIO interface
-- #phy-cells: must be 0
-
-This is a child bus node of "brcm,mdio-mux-iproc" node.
-
-Example:
-
-mdio@0 {
-	reg = <0x0>;
-	#address-cells = <1>;
-	#size-cells = <0>;
-
-	pci_phy0: pci-phy@0 {
-		compatible = "brcm,ns2-pcie-phy";
-		reg = <0x0>;
-		#phy-cells = <0>;
-	};
-};

Documentation/devicetree/bindings/phy/brcm,ns2-pcie-phy.yaml

···
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/brcm,ns2-pcie-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom NS2 PCIe PHY binding document
+
+maintainers:
+  - Ray Jui <[e-mail]>
+  - Scott Branden <[e-mail]>
+
+properties:
+  compatible:
+    const: brcm,ns2-pcie-phy
+
+  reg:
+    maxItems: 1
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    mdio {
+       #address-cells = <1>;
+       #size-cells = <0>;
+
+       pci-phy@0 {
+          compatible = "brcm,ns2-pcie-phy";
+          reg = <0x0>;
+          #phy-cells = <0>;
+       };
+    };