staging: iio: adc: ad7280a: fix overwrite of the returned value

The ret returned from ad7280_chain_setup() is needed to initialize the
slave_num. Don't overwrite it with call to devm_add_action_or_reset().

Fixes: cc9c58ef6e ("staging: iio: adc: ad7280a: use devm_* APIs")
Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/adc/ad7280a.c

@@ -879,15 +879,15 @@ static int ad7280_probe(struct spi_device *spi)
 	if (ret < 0)
 		return ret;
 
-	ret = devm_add_action_or_reset(&spi->dev, ad7280_sw_power_down, st);
-	if (ret)
-		return ret;
-
 	st->slave_num = ret;
 	st->scan_cnt = (st->slave_num + 1) * AD7280A_NUM_CH;
 	st->cell_threshhigh = 0xFF;
 	st->aux_threshhigh = 0xFF;
 
+	ret = devm_add_action_or_reset(&spi->dev, ad7280_sw_power_down, st);
+	if (ret)
+		return ret;
+
 	/*
 	 * Total Conversion Time = ((tACQ + tCONV) *
 	 *			   (Number of Conversions per Part)) −