ALSA: firewire: Constify snd_rawmidi_ops

Now snd_rawmidi_ops is maintained as a const pointer in snd_rawmidi,
we can constify the definitions.

Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/bebob/bebob_midi.c

@@ -120,12 +120,12 @@ static void set_midi_substream_names(struct snd_bebob *bebob,
 
 int snd_bebob_create_midi_devices(struct snd_bebob *bebob)
 {
-	static struct snd_rawmidi_ops capture_ops = {
+	static const struct snd_rawmidi_ops capture_ops = {
 		.open		= midi_capture_open,
 		.close		= midi_capture_close,
 		.trigger	= midi_capture_trigger,
 	};
-	static struct snd_rawmidi_ops playback_ops = {
+	static const struct snd_rawmidi_ops playback_ops = {
 		.open		= midi_playback_open,
 		.close		= midi_playback_close,
 		.trigger	= midi_playback_trigger,