iio: max31865: 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 ``in_filter_notch_center_frequency`
and fault_ovuv` device attributes of the max31865 driver.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20211216185217.1054495-10-lars@metafoo.deSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/temperature/max31865.c

@@ -208,7 +208,7 @@ static ssize_t show_fault(struct device *dev, u8 faultbit, char *buf)
 
 	fault = data->buf[0] & faultbit;
 
-	return sprintf(buf, "%d\n", fault);
+	return sysfs_emit(buf, "%d\n", fault);
 }
 
 static ssize_t show_fault_ovuv(struct device *dev,
@@ -225,7 +225,7 @@ static ssize_t show_filter(struct device *dev,
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct max31865_data *data = iio_priv(indio_dev);
 
-	return sprintf(buf, "%d\n", data->filter_50hz ? 50 : 60);
+	return sysfs_emit(buf, "%d\n", data->filter_50hz ? 50 : 60);
 }
 
 static ssize_t set_filter(struct device *dev,