V4L/DVB (9743): em28xx: fix oops audio

Replaced usb_kill_usb for usb_unlink_usb
(wait until urb to fully stop require USB core to put the calling process to sleep).

Oops:
http://www.kerneloops.org/raw.php?rawid=71799&msgid=Signed-off-by: Douglas Schilling Landgraf <dougsland@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/em28xx/em28xx-audio.c

@@ -62,7 +62,7 @@ static int em28xx_isoc_audio_deinit(struct em28xx *dev)
 
 	dprintk("Stopping isoc\n");
 	for (i = 0; i < EM28XX_AUDIO_BUFS; i++) {
-		usb_kill_urb(dev->adev->urb[i]);
+		usb_unlink_urb(dev->adev->urb[i]);
 		usb_free_urb(dev->adev->urb[i]);
 		dev->adev->urb[i] = NULL;
 	}