ALSA: sb16: constify pnp_card_device_id

pnp_card_device_id are not supposed to change at runtime. All functions
working with pnp_card_device_id provided by <linux/pnp.h> work with
const pnp_card_device_id. So mark the non-const structs as const.
Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/sb/sb16.c

@@ -145,7 +145,7 @@ struct snd_card_sb16 {
 
 #ifdef CONFIG_PNP
 
-static struct pnp_card_device_id snd_sb16_pnpids[] = {
+static const struct pnp_card_device_id snd_sb16_pnpids[] = {
 #ifndef SNDRV_SBAWE
 	/* Sound Blaster 16 PnP */
 	{ .id = "CTL0024", .devs = { { "CTL0031" } } },