iio: Drop timestamp parameter from buffer store_to callback

Drop timestamp parameter from buffer store_to callback and subsequently from
iio_push_to_buffer. The timestamp parameter is unused and it seems likely that
it will stay unused in the future, so it should be safe to remove it.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 774891c..d4ad374 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -682,12 +682,11 @@
 	return buffer->demux_bounce;
 }
 
-int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
-		       s64 timestamp)
+int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data)
 {
 	unsigned char *dataout = iio_demux(buffer, data);
 
-	return buffer->access->store_to(buffer, dataout, timestamp);
+	return buffer->access->store_to(buffer, dataout);
 }
 EXPORT_SYMBOL_GPL(iio_push_to_buffer);