dt-bindings: i2c: npcm7xx: add NPCM I2C controller

Added device tree binding documentation for Nuvoton BMC
NPCM I2C controller.
Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

Documentation/devicetree/bindings/i2c/nuvoton,npcm7xx-i2c.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/nuvoton,npcm7xx-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: nuvoton NPCM7XX I2C Controller Device Tree Bindings
+
+description: |
+  The NPCM750x includes sixteen I2C bus controllers. All Controllers support
+  both master and slave mode. Each controller can switch between master and slave
+  at run time (i.e. IPMB mode). Each controller has two 16 byte HW FIFO for TX and
+  RX.
+
+maintainers:
+  - Tali Perry <tali.perry1@gmail.com>
+
+properties:
+  compatible:
+    const: nuvoton,npcm7xx-i2c
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description: Reference clock for the I2C bus
+
+  clock-frequency:
+    description: Desired I2C bus clock frequency in Hz. If not specified,
+                 the default 100 kHz frequency will be used.
+                 possible values are 100000, 400000 and 1000000.
+    default: 100000
+    enum: [100000, 400000, 1000000]
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/nuvoton,npcm7xx-clock.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    i2c0: i2c@80000 {
+        reg = <0x80000 0x1000>;
+        clocks = <&clk NPCM7XX_CLK_APB2>;
+        clock-frequency = <100000>;
+        interrupts = <GIC_SPI 64 IRQ_TYPE_LEVEL_HIGH>;
+        compatible = "nuvoton,npcm750-i2c";
+    };
+
+...