[media] usbvision-video: fix memory leak of alt_max_pkt_size

1. usbvision->alt_max_pkt_size is not deallocated anywhere.
2. if allocation of usbvision->alt_max_pkt_size fails,
there is no proper deallocation of already acquired resources.
The patch adds kfree(usbvision->alt_max_pkt_size) to
usbvision_release() as soon as other deallocations happen there.
It calls usbvision_release() if allocation of
usbvision->alt_max_pkt_size fails as soon as usbvision_release()
is safe to work with incompletely initialized usbvision structure.
Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/usb/usbvision/usbvision-video.c

···
 
 	usbvision_remove_sysfs(usbvision->vdev);
 	usbvision_unregister_video(usbvision);
+	kfree(usbvision->alt_max_pkt_size);
 
 	usb_free_urb(usbvision->ctrl_urb);
 
···
 	usbvision->alt_max_pkt_size = kmalloc(32 * usbvision->num_alt, GFP_KERNEL);
 	if (usbvision->alt_max_pkt_size == NULL) {
 		dev_err(&intf->dev, "usbvision: out of memory!\n");
+		usbvision_release(usbvision);
 		return -ENOMEM;
 	}