iio: st_sensors: do not always write enable_axis register

New devices (e.g. LIS2DW12) enable all axis by default and do not export
that capability in register map. Check if the enable_axis register
address has been declared in st_sensor_settings map in order to verify if
the driver needs to enable all sensor axis

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/common/st_sensors/st_sensors_core.c

@@ -221,11 +221,14 @@ EXPORT_SYMBOL(st_sensors_set_enable);
 int st_sensors_set_axis_enable(struct iio_dev *indio_dev, u8 axis_enable)
 {
 	struct st_sensor_data *sdata = iio_priv(indio_dev);
+	int err = 0;
 
-	return st_sensors_write_data_with_mask(indio_dev,
+	if (sdata->sensor_settings->enable_axis.addr)
+		err = st_sensors_write_data_with_mask(indio_dev,
 				sdata->sensor_settings->enable_axis.addr,
 				sdata->sensor_settings->enable_axis.mask,
 				axis_enable);
+	return err;
 }
 EXPORT_SYMBOL(st_sensors_set_axis_enable);