ALSA: pci: 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/20200103081714.9560-10-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/emu10k1/emu10k1_main.c b/sound/pci/emu10k1/emu10k1_main.c
index 65e9ec9..6a8fce8 100644
--- a/sound/pci/emu10k1/emu10k1_main.c
+++ b/sound/pci/emu10k1/emu10k1_main.c
@@ -1791,7 +1791,7 @@ int snd_emu10k1_create(struct snd_card *card,
 	size_t page_table_size;
 	unsigned int silent_page;
 	const struct snd_emu_chip_details *c;
-	static struct snd_device_ops ops = {
+	static const struct snd_device_ops ops = {
 		.dev_free =	snd_emu10k1_dev_free,
 	};