dt-bindings: trivial-devices: document the Sierra Wireless mangOH Green SPI IoT interface

Document the Sierra Wireless mangOH Green SPI IoT interface as a trivial
device.

This fixes the following check:
qcom-mdm9615-wp8548-mangoh-green.dtb: /soc/gsbi@16200000/spi@16280000/spi@0: failed to match any schema with compatible: ['swir,mangoh-iotport-spi']
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240710-topic-mdm9615-mangoh-iotport-spi-bindings-v1-1-3efe20cfea8a@linaro.orgSigned-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -354,6 +354,8 @@ properties:
           - sparkfun,qwiic-joystick
             # i2c serial eeprom (24cxx)
           - st,24c256
+            # Sierra Wireless mangOH Green SPI IoT interface
+          - swir,mangoh-iotport-spi
             # Ambient Light Sensor with SMBUS/Two Wire Serial Interface
           - taos,tsl2550
             # Temperature Monitoring and Fan Control