dt-bindings: interrupt-controller: Add Amazon's Annapurna Labs FIC

Amazon's Annapurna Labs Fabric Interrupt Controller

Required properties:

- compatible: should be "amazon,al-fic"

- reg: physical base address and size of the registers

- interrupt-controller: identifies the node as an interrupt controller

- #interrupt-cells: must be 2.

  First cell defines the index of the interrupt within the controller.

  Second cell is used to specify the trigger type and must be one of the

  following:

    - bits[3:0] trigger type and level flags

	1 = low-to-high edge triggered

	4 = active high level-sensitive

- interrupt-parent: specifies the parent interrupt controller.

- interrupts: describes which input line in the interrupt parent, this

  fic's output is connected to. This field property depends on the parent's

  binding

Example:

amazon_fic: interrupt-controller@0xfd8a8500 {

	compatible = "amazon,al-fic";

	interrupt-controller;

	#interrupt-cells = <2>;

	reg = <0x0 0xfd8a8500 0x0 0x1000>;

	interrupt-parent = <&gic>;

	interrupts = <GIC_SPI 0x0 IRQ_TYPE_LEVEL_HIGH>;

};