iio: industrialio-buffer: fix possible '-Wuninitialized'

In case 'if (!indio_dev->info)' evaluates to true, 'ret' would be used
uninitialized. Initialize it to '-ENODEV'.

Fixes: 2249f29 ("iio: buffer: support multiple high speed buffers per device")
Signed-off-by: Nuno Sa <nuno.sa@analog.com>

Author: nunojsa

drivers/iio/industrialio-buffer.c

@@ -1711,7 +1711,7 @@ static long iio_buffer_ioctl_wrapper(struct file *filp, unsigned int cmd,
 	struct iio_dev_buffer_pair *ib = filp->private_data;
 	struct iio_dev *indio_dev = ib->indio_dev;
 	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
-	int ret;
+	int ret = -ENODEV;
 
 	mutex_lock(&iio_dev_opaque->info_exist_lock);