dt-bindings:iio:magnetometer:memsic,mmc35240: move to trivial-devices.yaml

Extremely simple binding so no need to maintain a separate file.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Jandy Gou <qingsong.gou@ck-telecom.com>
Link: https://lore.kernel.org/r/20201031182922.743153-7-jic23@kernel.org

Documentation/devicetree/bindings/iio/magnetometer/mmc35240.txt

-* MEMSIC MMC35240 magnetometer sensor
-
-Required properties:
-
-  - compatible : should be "memsic,mmc35240"
-  - reg : the I2C address of the magnetometer
-
-Example:
-
-mmc35240@30 {
-        compatible = "memsic,mmc35240";
-        reg = <0x30>;
-};

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -142,6 +142,8 @@ properties:
           - maxim,max31730
             # mCube 3-axis 8-bit digital accelerometer
           - mcube,mc3230
+            # MEMSIC magnetometer
+          - memsic,mmc35240
             # MEMSIC 2-axis 8-bit digital accelerometer
           - memsic,mxc6225
             # Measurement Specialities I2C temperature and humidity sensor