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/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index c1e4690..bc10091 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -82,7 +82,7 @@
 		*timestamp = pf->timestamp;
 	}
 
-	buffer->access->store_to(buffer, (u8 *)st->buffer, pf->timestamp);
+	buffer->access->store_to(buffer, (u8 *)st->buffer);
 
 	iio_trigger_notify_done(idev->trig);
 	st->irq_enabled = true;