dt-bindings: interrupt-controller: Convert brcm,bcm6345-l1-intc to DT schema

Convert the Broadcom BCM6345 interrupt controller binding to schema
format.

The old schema indicated SoC specific compatibles should be present, but
there are none in use. So drop them.

The most number of CPUs on any platform seems to be 2, so document that
as the maximum.

Link: https://lore.kernel.org/r/20250505144622.1287712-1-robh@kernel.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Author: robherring

Documentation/devicetree/bindings/interrupt-controller/brcm,bcm6345-l1-intc.txt

@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interrupt-controller/brcm,bcm6345-l1-intc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom BCM6345-style Level 1 interrupt controller
+
+maintainers:
+  - Simon Arlott <simon@octiron.net>
+
+description: >
+  This block is a first level interrupt controller that is typically connected
+  directly to one of the HW INT lines on each CPU.
+
+  Key elements of the hardware design include:
+
+    - 32, 64 or 128 incoming level IRQ lines
+
+    - Most onchip peripherals are wired directly to an L1 input
+
+    - A separate instance of the register set for each CPU, allowing individual
+      peripheral IRQs to be routed to any CPU
+
+    - Contains one or more enable/status word pairs per CPU
+
+    - No atomic set/clear operations
+
+    - No polarity/level/edge settings
+
+    - No FIFO or priority encoder logic; software is expected to read all
+      2-4 status words to determine which IRQs are pending
+
+  If multiple reg ranges and interrupt-parent entries are present on an SMP
+  system, the driver will allow IRQ SMP affinity to be set up through the
+  /proc/irq/ interface.  In the simplest possible configuration, only one
+  reg range and one interrupt-parent is needed.
+
+  The driver operates in native CPU endian by default, there is no support for
+  specifying an alternative endianness.
+
+properties:
+  compatible:
+    const: brcm,bcm6345-l1-intc
+
+  reg:
+    description: One entry per CPU core
+    minItems: 1
+    maxItems: 2
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 1
+
+  interrupts:
+    description: One entry per CPU core
+    minItems: 1
+    maxItems: 2
+
+required:
+  - compatible
+  - reg
+  - interrupt-controller
+  - '#interrupt-cells'
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    interrupt-controller@10000000 {
+        compatible = "brcm,bcm6345-l1-intc";
+        reg = <0x10000020 0x20>,
+              <0x10000040 0x20>;
+
+        interrupt-controller;
+        #interrupt-cells = <1>;
+
+        interrupts = <2>, <3>;
+    };