iio: adc: max1027: Simplify the _set_trigger_state() helper

The call to max1027_enable_trigger() is the same in both cases thanks to
the 'state' variable, so factorize a little bit to simplify the code and
explain why we call this helper.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20210921115408.66711-8-miquel.raynal@bootlin.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/max1027.c

@@ -410,11 +410,17 @@ static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig, bool state)
 	struct max1027_state *st = iio_priv(indio_dev);
 	int ret;
 
-	if (state) {
-		ret = max1027_enable_trigger(indio_dev, state);
-		if (ret)
-			return ret;
+	/*
+	 * In order to disable the convst trigger, start acquisition on
+	 * conversion register write, which basically disables triggering
+	 * conversions upon cnvst changes and thus has the effect of disabling
+	 * the external hardware trigger.
+	 */
+	ret = max1027_enable_trigger(indio_dev, state);
+	if (ret)
+		return ret;
 
+	if (state) {
 		/*
 		 * Scan from chan 0 to the highest requested channel.
 		 * Include temperature on demand.
@@ -427,11 +433,6 @@ static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig, bool state)
 		ret = spi_write(st->spi, &st->reg, 1);
 		if (ret < 0)
 			return ret;
-	} else {
-		/* Start acquisition on conversion register write */
-		ret = max1027_enable_trigger(indio_dev, state);
-		if (ret)
-			return ret;
 	}
 
 	return 0;