binding: PHY: Binding doc for NS2 PCIe PHYs.

Binding doc for NS2 PCIe PHYs.
Signed-off-by: NPramod Kumar <pramod.kumar@broadcom.com>
Signed-off-by: NJon Mason <jonmason@broadcom.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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>;
+	};
+};