staging: bcm2835-audio: off by one in snd_bcm2835_playback_open_generic()

The > should be >= otherwise we write beyond the end of the array when
we do:

	chip->alsa_stream[idx] = alsa_stream;

Fixes: 23b028c8 ("staging: bcm2835-audio: initial staging submission")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/bcm2835-audio/bcm2835-pcm.c

@@ -130,7 +130,7 @@ static int snd_bcm2835_playback_open_generic(
 		err = -EBUSY;
 		goto out;
 	}
-	if (idx > MAX_SUBSTREAMS) {
+	if (idx >= MAX_SUBSTREAMS) {
 		audio_error
 			("substream(%d) device doesn't exist max(%d) substreams allowed\n",
 			idx, MAX_SUBSTREAMS);