V4L/DVB: cx18-alsa: fix memory leak in error condition

If the stream is already in use, make sure we free up the memory allocated
earlier.

Thanks to Andy Wall for reviewing and pointing this out.

This work was sponsored by ONELAN Limited.
Signed-off-by: NDevin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-alsa-pcm.c

@@ -95,6 +95,7 @@ static int snd_cx18_pcm_capture_open(struct snd_pcm_substream *substream)
 	/* See if the stream is available */
 	if (cx18_claim_stream(item, item->type)) {
 		/* No, it's already in use */
+		kfree(item);
 		return -EBUSY;
 	}