ALSA: drivers: Constify snd_device_ops definitions

Now we may declare const for snd_device_ops definitions, so let's do
it for optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-6-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/ml403-ac97cr.c

@@ -1076,7 +1076,7 @@ snd_ml403_ac97cr_create(struct snd_card *card, struct platform_device *pfdev,
 {
 	struct snd_ml403_ac97cr *ml403_ac97cr;
 	int err;
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free = snd_ml403_ac97cr_dev_free,
 	};
 	struct resource *resource;

sound/drivers/opl3/opl3_lib.c

@@ -332,7 +332,7 @@ int snd_opl3_new(struct snd_card *card,
 		 unsigned short hardware,
 		 struct snd_opl3 **ropl3)
 {
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free = snd_opl3_dev_free,
 	};
 	struct snd_opl3 *opl3;

sound/drivers/opl4/opl4_lib.c

@@ -184,7 +184,7 @@ int snd_opl4_create(struct snd_card *card,
 	struct snd_opl4 *opl4;
 	struct snd_opl3 *opl3;
 	int err;
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free = snd_opl4_dev_free
 	};
 

sound/drivers/pcsp/pcsp.c

@@ -43,7 +43,7 @@ struct snd_pcsp pcsp_chip;
 
 static int snd_pcsp_create(struct snd_card *card)
 {
-	static struct snd_device_ops ops = { };
+	static const struct snd_device_ops ops = { };
 	unsigned int resolution = hrtimer_resolution;
 	int err, div, min_div, order;
 

sound/drivers/serial-u16550.c

@@ -777,7 +777,7 @@ static int snd_uart16550_create(struct snd_card *card,
 				int droponfull,
 				struct snd_uart16550 **ruart)
 {
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free =	snd_uart16550_dev_free,
 	};
 	struct snd_uart16550 *uart;