dt-bindings: spi: axi-spi-engine: convert to yaml

This converts the axi-spi-engine binding to yaml.

There are a few minor fixes in the conversion:
* Added maintainers.
* Added descriptions for the clocks.
* Fixed the double "@" in the example.
* Added a comma between the clocks in the example.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231117-axi-spi-engine-series-1-v1-1-cc59db999b87@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/adi,axi-spi-engine.txt

-Analog Devices AXI SPI Engine controller Device Tree Bindings
-
-Required properties:
-- compatible		: Must be "adi,axi-spi-engine-1.00.a""
-- reg			: Physical base address and size of the register map.
-- interrupts		: Property with a value describing the interrupt
-			  number.
-- clock-names		: List of input clock names - "s_axi_aclk", "spi_clk"
-- clocks		: Clock phandles and specifiers (See clock bindings for
-			  details on clock-names and clocks).
-- #address-cells	: Must be <1>
-- #size-cells		: Must be <0>
-
-Optional subnodes:
-	Subnodes are use to represent the SPI slave devices connected to the SPI
-	master. They follow the generic SPI bindings as outlined in spi-bus.txt.
-
-Example:
-
-    spi@@44a00000 {
-		compatible = "adi,axi-spi-engine-1.00.a";
-		reg = <0x44a00000 0x1000>;
-		interrupts = <0 56 4>;
-		clocks = <&clkc 15 &clkc 15>;
-		clock-names = "s_axi_aclk", "spi_clk";
-
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		/* SPI devices */
-    };

Documentation/devicetree/bindings/spi/adi,axi-spi-engine.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/adi,axi-spi-engine.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AXI SPI Engine Controller
+
+description: |
+  The AXI SPI Engine controller is part of the SPI Engine framework[1] and
+  allows memory mapped access to the SPI Engine control bus. This allows it
+  to be used as a general purpose software driven SPI controller as well as
+  some optional advanced acceleration and offloading capabilities.
+
+  [1] https://wiki.analog.com/resources/fpga/peripherals/spi_engine
+
+maintainers:
+  - Michael Hennerich <Michael.Hennerich@analog.com>
+  - Nuno Sá <nuno.sa@analog.com>
+
+allOf:
+  - $ref: /schemas/spi/spi-controller.yaml#
+
+properties:
+  compatible:
+    const: adi,axi-spi-engine-1.00.a
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: The AXI interconnect clock.
+      - description: The SPI controller clock.
+
+  clock-names:
+    items:
+      - const: s_axi_aclk
+      - const: spi_clk
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    spi@44a00000 {
+        compatible = "adi,axi-spi-engine-1.00.a";
+        reg = <0x44a00000 0x1000>;
+        interrupts = <0 56 4>;
+        clocks = <&clkc 15>, <&clkc 15>;
+        clock-names = "s_axi_aclk", "spi_clk";
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        /* SPI devices */
+    };