ALSA: fireface: Off by one in latter_handle_midi_msg()

The > should be >= or otherwise we potentially read one element beyond
the end of the ff->tx_midi_substreams[] array.

Fixes: 73f5537f ("ALSA: fireface: support tx MIDI functionality of Fireface UCX")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/fireface/ff-protocol-latter.c

@@ -293,7 +293,7 @@ static void latter_handle_midi_msg(struct snd_ff *ff, unsigned int offset,
 	struct snd_rawmidi_substream *substream;
 	unsigned int len;
 
-	if (index > ff->spec->midi_in_ports)
+	if (index >= ff->spec->midi_in_ports)
 		return;
 
 	switch (data & 0x0000000f) {