dt-bindings: mmc: npcm,sdhci: Document NPCM SDHCI controller

Add binding for Nuvoton NPCM SDHCI controller.
Signed-off-by: Tomer Maimon <tmaimon77@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231002200610.129799-2-tmaimon77@gmail.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/npcm,sdhci.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mmc/npcm,sdhci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NPCM SDHCI Controller
+
+maintainers:
+  - Tomer Maimon <tmaimon77@gmail.com>
+
+allOf:
+  - $ref: mmc-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,npcm750-sdhci
+      - nuvoton,npcm845-sdhci
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    mmc@f0840000 {
+      compatible = "nuvoton,npcm750-sdhci";
+      reg = <0xf0840000 0x200>;
+      interrupts = <0 27 4>;
+      clocks = <&clk 4>;
+    };