Driver for ARM AXI Bus with Broadcom Plugins (bcma)

Required properties:

- compatible : brcm,bus-axi

- reg : iomem address range of chipcommon core

The cores on the AXI bus are automatically detected by bcma with the
memory ranges they are using and they get registered afterwards.

The top-level axi bus may contain children representing attached cores
(devices). This is needed since some hardware details can't be auto
detected (e.g. IRQ numbers). Also some of the cores may be responsible
for extra things, e.g. ChipCommon providing access to the GPIO chip.

Example:

	axi@18000000 {
		compatible = "brcm,bus-axi";
		reg = <0x18000000 0x1000>;
		ranges = <0x00000000 0x18000000 0x00100000>;
		#address-cells = <1>;
		#size-cells = <1>;

		chipcommon {
			reg = <0x00000000 0x1000>;

			gpio-controller;
			#gpio-cells = <2>;
		};
	};
