staging: iio: ad9834: add a check for devm_clk_get

ad9834_probe misses a check for devm_clk_get and may cause problems.
Add a check like what ad9832 does to fix it.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/frequency/ad9834.c

@@ -417,6 +417,10 @@ static int ad9834_probe(struct spi_device *spi)
 	st = iio_priv(indio_dev);
 	mutex_init(&st->lock);
 	st->mclk = devm_clk_get(&spi->dev, NULL);
+	if (IS_ERR(st->mclk)) {
+		ret = PTR_ERR(st->mclk);
+		goto error_disable_reg;
+	}
 
 	ret = clk_prepare_enable(st->mclk);
 	if (ret) {