iio: ad7192: Use sysfs_emit()

sysfs_emit() is preferred over raw s*printf() for sysfs attributes since it
knows about the sysfs buffer specifics and has some built-in checks for
size and alignment.

Use sysfs_emit() to format the custom `ac_excitation` and `bridge_swtich`
attributes of the ad7192 driver.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20211216185217.1054495-4-lars@metafoo.deSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -433,7 +433,7 @@ static ssize_t ad7192_show_ac_excitation(struct device *dev,
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ad7192_state *st = iio_priv(indio_dev);
 
-	return sprintf(buf, "%d\n", !!(st->mode & AD7192_MODE_ACX));
+	return sysfs_emit(buf, "%d\n", !!(st->mode & AD7192_MODE_ACX));
 }
 
 static ssize_t ad7192_show_bridge_switch(struct device *dev,
@@ -443,7 +443,7 @@ static ssize_t ad7192_show_bridge_switch(struct device *dev,
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ad7192_state *st = iio_priv(indio_dev);
 
-	return sprintf(buf, "%d\n", !!(st->gpocon & AD7192_GPOCON_BPDSW));
+	return sysfs_emit(buf, "%d\n", !!(st->gpocon & AD7192_GPOCON_BPDSW));
 }
 
 static ssize_t ad7192_set(struct device *dev,