Aardvark PCIe controller

This PCIe controller is used on the Marvell Armada 3700 ARM64 SoC.

The Device Tree node describing an Aardvark PCIe controller must
contain the following properties:

 - compatible: Should be "marvell,armada-3700-pcie"
 - reg: range of registers for the PCIe controller
 - interrupts: the interrupt line of the PCIe controller
 - #address-cells: set to <3>
 - #size-cells: set to <2>
 - device_type: set to "pci"
 - ranges: ranges for the PCI memory and I/O regions
 - #interrupt-cells: set to <1>
 - msi-controller: indicates that the PCIe controller can itself
   handle MSI interrupts
 - msi-parent: pointer to the MSI controller to be used
 - interrupt-map-mask and interrupt-map: standard PCI properties to
   define the mapping of the PCIe interface to interrupt numbers.
 - bus-range: PCI bus numbers covered

In addition, the Device Tree describing an Aardvark PCIe controller
must include a sub-node that describes the legacy interrupt controller
built into the PCIe controller. This sub-node must have the following
properties:

 - interrupt-controller
 - #interrupt-cells: set to <1>

Example:

	pcie0: pcie@d0070000 {
		compatible = "marvell,armada-3700-pcie";
		device_type = "pci";
		status = "disabled";
		reg = <0 0xd0070000 0 0x20000>;
		#address-cells = <3>;
		#size-cells = <2>;
		bus-range = <0x00 0xff>;
		interrupts = <GIC_SPI 29 IRQ_TYPE_LEVEL_HIGH>;
		#interrupt-cells = <1>;
		msi-controller;
		msi-parent = <&pcie0>;
		ranges = <0x82000000 0 0xe8000000   0 0xe8000000 0 0x1000000 /* Port 0 MEM */
			  0x81000000 0 0xe9000000   0 0xe9000000 0 0x10000>; /* Port 0 IO*/
		interrupt-map-mask = <0 0 0 7>;
		interrupt-map = <0 0 0 1 &pcie_intc 0>,
				<0 0 0 2 &pcie_intc 1>,
				<0 0 0 3 &pcie_intc 2>,
				<0 0 0 4 &pcie_intc 3>;
		pcie_intc: interrupt-controller {
			interrupt-controller;
			#interrupt-cells = <1>;
		};
	};