* Mediatek 27xx cirq

In Mediatek SOCs, the CIRQ is a low power interrupt controller designed to
work outside MCUSYS which comprises with Cortex-Ax cores,CCI and GIC.
The external interrupts (outside MCUSYS) will feed through CIRQ and connect
to GIC in MCUSYS. When CIRQ is enabled, it will record the edge-sensitive
interrupts and generate a pulse signal to parent interrupt controller when
flush command is executed. With CIRQ, MCUSYS can be completely turned off
to improve the system power consumption without losing interrupts.

Required properties:
- compatible: should be one of
  - "mediatek,mt2701-cirq" for mt2701 CIRQ
  - "mediatek,mt8135-cirq" for mt8135 CIRQ
  - "mediatek,mt8173-cirq" for mt8173 CIRQ
  and "mediatek,cirq" as a fallback.
- interrupt-controller : Identifies the node as an interrupt controller.
- #interrupt-cells : Use the same format as specified by GIC in arm,gic.txt.
- reg: Physical base address of the cirq registers and length of memory
  mapped region.
- mediatek,ext-irq-range: Identifies external irq number range in different
  SOCs.

Example:
	cirq: interrupt-controller@10204000 {
		compatible = "mediatek,mt2701-cirq",
			     "mediatek,mtk-cirq";
		interrupt-controller;
		#interrupt-cells = <3>;
		interrupt-parent = <&sysirq>;
		reg = <0 0x10204000 0 0x400>;
		mediatek,ext-irq-start = <32 200>;
	};
