iio: adc: at91-sama5d2_adc: use sysfs_emit() to instead of scnprintf()

Replace the open-code with sysfs_emit() to simplify the code.
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/202212011142333790361@zte.com.cnSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/at91-sama5d2_adc.c

@@ -2181,7 +2181,7 @@ static ssize_t at91_adc_get_fifo_state(struct device *dev,
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct at91_adc_state *st = iio_priv(indio_dev);
 
-	return scnprintf(buf, PAGE_SIZE, "%d\n", !!st->dma_st.dma_chan);
+	return sysfs_emit(buf, "%d\n", !!st->dma_st.dma_chan);
 }
 
 static ssize_t at91_adc_get_watermark(struct device *dev,
@@ -2190,7 +2190,7 @@ static ssize_t at91_adc_get_watermark(struct device *dev,
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct at91_adc_state *st = iio_priv(indio_dev);
 
-	return scnprintf(buf, PAGE_SIZE, "%d\n", st->dma_st.watermark);
+	return sysfs_emit(buf, "%d\n", st->dma_st.watermark);
 }
 
 static IIO_DEVICE_ATTR(hwfifo_enabled, 0444,