staging: iio: adis16060_core: Fix error handling

We need to check adis16060_spi_read return code to avoid feeding user
space with bogus data.
While, at it introduce out_unlock label in order to simplify locking
on error path.
Signed-off-by: Cristina Moraru <cristina.moraru09@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/iio/gyro/adis16060_core.c

@@ -89,11 +89,13 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
 		/* Take the iio_dev status lock */
 		mutex_lock(&indio_dev->mlock);
 		ret = adis16060_spi_write(indio_dev, chan->address);
-		if (ret < 0) {
-			mutex_unlock(&indio_dev->mlock);
-			return ret;
-		}
+		if (ret < 0)
+			goto out_unlock;
+
 		ret = adis16060_spi_read(indio_dev, &tval);
+		if (ret < 0)
+			goto out_unlock;
+
 		mutex_unlock(&indio_dev->mlock);
 		*val = tval;
 		return IIO_VAL_INT;
@@ -108,6 +110,10 @@ static int adis16060_read_raw(struct iio_dev *indio_dev,
 	}
 
 	return -EINVAL;
+
+out_unlock:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
 }
 
 static const struct iio_info adis16060_info = {