dt-bindings: interrupt-controller: Add MStar interrupt controller

Add binding for MStar interrupt controller.
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200902063344.1852-3-mark-pk.tsai@mediatek.com

Documentation/devicetree/bindings/interrupt-controller/mstar,mst-intc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interrupt-controller/mstar,mst-intc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MStar Interrupt Controller
+
+maintainers:
+  - Mark-PK Tsai <mark-pk.tsai@mediatek.com>
+
+description: |+
+  MStar, SigmaStar and Mediatek TV SoCs contain multiple legacy
+  interrupt controllers that routes interrupts to the GIC.
+
+  The HW block exposes a number of interrupt controllers, each
+  can support up to 64 interrupts.
+
+properties:
+  compatible:
+    const: mstar,mst-intc
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 3
+    description: |
+      Use the same format as specified by GIC in arm,gic.yaml.
+
+  reg:
+    maxItems: 1
+
+  mstar,irqs-map-range:
+    description: |
+      The range <start, end> of parent interrupt controller's interrupt
+      lines that are hardwired to mstar interrupt controller.
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    items:
+      minItems: 2
+      maxItems: 2
+
+  mstar,intc-no-eoi:
+    description:
+      Mark this controller has no End Of Interrupt(EOI) implementation.
+    type: boolean
+
+required:
+  - compatible
+  - reg
+  - mstar,irqs-map-range
+
+additionalProperties: false
+
+examples:
+  - |
+    mst_intc0: interrupt-controller@1f2032d0 {
+      compatible = "mstar,mst-intc";
+      interrupt-controller;
+      #interrupt-cells = <3>;
+      interrupt-parent = <&gic>;
+      reg = <0x1f2032d0 0x30>;
+      mstar,irqs-map-range = <0 63>;
+    };
+...