iio: adc: ad799x: add blank line to avoid warning messages

Add a blank line before if statement to avoid warning messages pointed by
checkpatch.

Co-developed-by: Bruna Lopes <brunaafl@usp.br>
Signed-off-by: Bruna Lopes <brunaafl@usp.br>
Signed-off-by: Gustavo Rodrigues <ogustavo@usp.br>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240428194326.2836387-3-ogustavo@usp.br
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad799x.c

@@ -335,6 +335,7 @@ static ssize_t ad799x_read_frequency(struct device *dev,
 	struct ad799x_state *st = iio_priv(indio_dev);
 
 	int ret = i2c_smbus_read_byte_data(st->client, AD7998_CYCLE_TMR_REG);
+
 	if (ret < 0)
 		return ret;