ALSA: midi: constify snd_rawmidi_global_ops structures

The snd_rawmidi_global_ops structures are never modified, so declare them
as const.

Done with the help of Coccinelle.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/rawmidi.h

@@ -130,7 +130,7 @@ struct snd_rawmidi {
 	int ossreg;
 #endif
 
-	struct snd_rawmidi_global_ops *ops;
+	const struct snd_rawmidi_global_ops *ops;
 
 	struct snd_rawmidi_str streams[2];
 

sound/core/seq/seq_virmidi.c

@@ -468,7 +468,7 @@ static int snd_virmidi_dev_unregister(struct snd_rawmidi *rmidi)
 /*
  *
  */
-static struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
+static const struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
 	.dev_register = snd_virmidi_dev_register,
 	.dev_unregister = snd_virmidi_dev_unregister,
 };

sound/usb/midi.c

@@ -2206,7 +2206,7 @@ static int snd_usbmidi_create_endpoints_midiman(struct snd_usb_midi *umidi,
 	return 0;
 }
 
-static struct snd_rawmidi_global_ops snd_usbmidi_ops = {
+static const struct snd_rawmidi_global_ops snd_usbmidi_ops = {
 	.get_port_info = snd_usbmidi_get_port_info,
 };