spi: dt-bindings: airoha: Add YAML schema for SNFI controller

Introduce Airoha EN7581 SPI NAND controller binding
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Rajeev Kumar <Rajeev.Kumar@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/f3377b323f00589e6b7ed7950c4840d18129238b.1714377864.git.lorenzo@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/airoha,en7581-snand.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/airoha,en7581-snand.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SPI-NAND flash controller for Airoha ARM SoCs
+
+maintainers:
+  - Lorenzo Bianconi <lorenzo@kernel.org>
+
+allOf:
+  - $ref: spi-controller.yaml#
+
+properties:
+  compatible:
+    const: airoha,en7581-snand
+
+  reg:
+    items:
+      - description: spi base address
+      - description: nfi2spi base address
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: spi
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/en7523-clk.h>
+
+    soc {
+      #address-cells = <2>;
+      #size-cells = <2>;
+
+      spi@1fa10000 {
+        compatible = "airoha,en7581-snand";
+        reg = <0x0 0x1fa10000 0x0 0x140>,
+              <0x0 0x1fa11000 0x0 0x160>;
+
+        clocks = <&scuclk EN7523_CLK_SPI>;
+        clock-names = "spi";
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        flash@0 {
+          compatible = "spi-nand";
+          reg = <0>;
+          spi-tx-bus-width = <1>;
+          spi-rx-bus-width = <2>;
+        };
+      };
+    };