ARM: dts: Cygnus: Update PCIe PHY node unit name(s)

Update the PCIe PHY node unit name and its sub-nodes to help with
upcoming changes converting the Cygnus PCIe PHY DT binding to YAML and
later the iProc PCIe controller binding to YAML.

Signed-off-by: Florian Fainelli <[e-mail]>

arch/arm/boot/dts/bcm-cygnus.dtsi

···
 			status = "disabled";
 		};
 
-		pcie_phy: phy@301d0a0 {
+		pcie_phy: pcie_phy@301d0a0 {
 			compatible = "brcm,cygnus-pcie-phy";
 			reg = <0x0301d0a0 0x14>;
 			#address-cells = <1>;
 			#size-cells = <0>;
 
-			pcie0_phy: phy@0 {
+			pcie0_phy: pcie-phy@0 {
 				reg = <0>;
 				#phy-cells = <0>;
 			};
 
-			pcie1_phy: phy@1 {
+			pcie1_phy: pcie-phy@1 {
 				reg = <1>;
 				#phy-cells = <0>;
 			};