dt-bindings: iio: adc: microchip,mcp3201: fix interface type (I2C -> SPI)

This family of ADCs uses SPI, not I2C.
Signed-off-by: Jan Luebbe <jlu@pengutronix.de>
Link: https://lore.kernel.org/r/20220216162312.4064-1-jlu@pengutronix.deSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/microchip,mcp3201.yaml

@@ -10,7 +10,7 @@ maintainers:
   - Oskar Andero <oskar.andero@gmail.com>
 
 description: |
-   Family of simple ADCs with an I2C inteface.
+   Family of simple ADCs with a SPI interface.
 
 properties:
   compatible: