iio: pressure: mprls0025pa fix off-by-one enum

Fix off-by-one error in transfer-function property.
The honeywell,transfer-function property takes values between 1-3 so
make sure the proper enum gets used.

Fixes: 713337d9 ("iio: pressure: Honeywell mprls0025pa pressure sensor")
Co-developed-by: Andreas Klinger <ak@it-klinger.de>
Signed-off-by: Andreas Klinger <ak@it-klinger.de>
Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
Link: https://lore.kernel.org/r/20231229092445.30180-5-petre.rodan@subdimension.roSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/pressure/mprls0025pa.c

@@ -323,6 +323,7 @@ static int mpr_probe(struct i2c_client *client)
 	struct iio_dev *indio_dev;
 	struct device *dev = &client->dev;
 	s64 scale, offset;
+	u32 func;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE))
 		return dev_err_probe(dev, -EOPNOTSUPP,
@@ -362,10 +363,11 @@ static int mpr_probe(struct i2c_client *client)
 			return dev_err_probe(dev, ret,
 				"honeywell,pmax-pascal could not be read\n");
 		ret = device_property_read_u32(dev,
-				"honeywell,transfer-function", &data->function);
+				"honeywell,transfer-function", &func);
 		if (ret)
 			return dev_err_probe(dev, ret,
 				"honeywell,transfer-function could not be read\n");
+		data->function = func - 1;
 		if (data->function > MPR_FUNCTION_C)
 			return dev_err_probe(dev, -EINVAL,
 				"honeywell,transfer-function %d invalid\n",