iio: buffer: Use IIO_SEPARATE instead of a hard-coded 0

Use an explicit IIO_SEPARATE instead of 0 for the 'shared_by' parameter
when calling __iio_add_chan_devattr().

For some reason, commit 3704432f ("iio: refactor info mask and ext_info
attribute creation.") updated only 1 place out of 4.
Update the remaining ones now.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/1d17f57423172fcb9d9797cfe7c8282f356049c2.1702831285.git.christophe.jaillet@wanadoo.frSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/industrialio-buffer.c

@@ -616,7 +616,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 				     &iio_show_fixed_type,
 				     NULL,
 				     0,
-				     0,
+				     IIO_SEPARATE,
 				     &indio_dev->dev,
 				     buffer,
 				     &buffer->buffer_attr_list);
@@ -629,7 +629,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 					     &iio_scan_el_show,
 					     &iio_scan_el_store,
 					     chan->scan_index,
-					     0,
+					     IIO_SEPARATE,
 					     &indio_dev->dev,
 					     buffer,
 					     &buffer->buffer_attr_list);
@@ -639,7 +639,7 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 					     &iio_scan_el_ts_show,
 					     &iio_scan_el_ts_store,
 					     chan->scan_index,
-					     0,
+					     IIO_SEPARATE,
 					     &indio_dev->dev,
 					     buffer,
 					     &buffer->buffer_attr_list);