iio: adc: Use complete() instead of complete_all()

There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

The usage pattern of the completion is:

waiter context                          waker context

nau7802_read_irq()
  reinit_completion()
  nau7802_read_conversion()
  wait_for_completion_interruptible_timeout()

                                        nau7802_eoc_trigger()
                                          complete()

Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/nau7802.c

@@ -197,7 +197,7 @@ static irqreturn_t nau7802_eoc_trigger(int irq, void *private)
 	if (st->conversion_count < NAU7802_MIN_CONVERSIONS)
 		st->conversion_count++;
 	if (st->conversion_count >= NAU7802_MIN_CONVERSIONS)
-		complete_all(&st->value_ok);
+		complete(&st->value_ok);
 
 	return IRQ_HANDLED;
 }