Mediatek Mt7621 PCIe PHY

Required properties:
- compatible: must be "mediatek,mt7621-pci-phy"
- reg: base address and length of the PCIe PHY block
- #phy-cells: must be <1> for pcie0_phy and for pcie1_phy.

Example:
	pcie0_phy: pcie-phy@1e149000 {
		compatible = "mediatek,mt7621-pci-phy";
		reg = <0x1e149000 0x0700>;
		#phy-cells = <1>;
	};

	pcie1_phy: pcie-phy@1e14a000 {
		compatible = "mediatek,mt7621-pci-phy";
		reg = <0x1e14a000 0x0700>;
		#phy-cells = <1>;
	};

	/* users of the PCIe phy */

	pcie: pcie@1e140000 {
		...
		...
		phys = <&pcie0_phy 0>, <&pcie0_phy 1>, <&pcie1_phy 0>;
		phy-names = "pcie-phy0", "pcie-phy1", "pcie-phy2";
	};