dt-bindings: interrupt-controller: Remove obsolete 'img,meta-intc'

The driver and metag arch were removed in 2018.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200826184851.3431531-3-robh@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/interrupt-controller/img,meta-intc.txt

-* Meta External Trigger Controller Binding
-
-This binding specifies what properties must be available in the device tree
-representation of a Meta external trigger controller.
-
-Required properties:
-
-    - compatible: Specifies the compatibility list for the interrupt controller.
-      The type shall be <string> and the value shall include "img,meta-intc".
-
-    - num-banks: Specifies the number of interrupt banks (each of which can
-      handle 32 interrupt sources).
-
-    - interrupt-controller: The presence of this property identifies the node
-      as an interrupt controller. No property value shall be defined.
-
-    - #interrupt-cells: Specifies the number of cells needed to encode an
-      interrupt source. The type shall be a <u32> and the value shall be 2.
-
-    - #address-cells: Specifies the number of cells needed to encode an
-      address. The type shall be <u32> and the value shall be 0. As such,
-      'interrupt-map' nodes do not have to specify a parent unit address.
-
-Optional properties:
-
-    - no-mask: The controller doesn't have any mask registers.
-
-* Interrupt Specifier Definition
-
-  Interrupt specifiers consists of 2 cells encoded as follows:
-
-    - <1st-cell>: The interrupt-number that identifies the interrupt source.
-
-    - <2nd-cell>: The Linux interrupt flags containing level-sense information,
-                  encoded as follows:
-                    1 = edge triggered
-                    4 = level-sensitive
-
-* Examples
-
-Example 1:
-
-	/*
-	 * Meta external trigger block
-	 */
-	intc: intc {
-		// This is an interrupt controller node.
-		interrupt-controller;
-
-		// No address cells so that 'interrupt-map' nodes which
-		// reference this interrupt controller node do not need a parent
-		// address specifier.
-		#address-cells = <0>;
-
-		// Two cells to encode interrupt sources.
-		#interrupt-cells = <2>;
-
-		// Number of interrupt banks
-		num-banks = <2>;
-
-		// No HWMASKEXT is available (specify on Chorus2 and Comet ES1)
-		no-mask;
-
-		// Compatible with Meta hardware trigger block.
-		compatible = "img,meta-intc";
-	};
-
-Example 2:
-
-	/*
-	 * An interrupt generating device that is wired to a Meta external
-	 * trigger block.
-	 */
-	uart1: uart@02004c00 {
-		// Interrupt source '5' that is level-sensitive.
-		// Note that there are only two cells as specified in the
-		// interrupt parent's '#interrupt-cells' property.
-		interrupts = <5 4 /* level */>;
-
-		// The interrupt controller that this device is wired to.
-		interrupt-parent = <&intc>;
-	};