ALSA: isa: Constify snd_kcontrol_new items

Most of snd_kcontrol_new definitions are read-only and passed as-is.
Let's declare them as const for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-36-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/isa/cmi8330.c b/sound/isa/cmi8330.c
index f8ec59a..61d6944 100644
--- a/sound/isa/cmi8330.c
+++ b/sound/isa/cmi8330.c
@@ -179,7 +179,7 @@ MODULE_DEVICE_TABLE(pnp_card, snd_cmi8330_pnpids);
 #endif
 
 
-static struct snd_kcontrol_new snd_cmi8330_controls[] = {
+static const struct snd_kcontrol_new snd_cmi8330_controls[] = {
 WSS_DOUBLE("Master Playback Volume", 0,
 		CMI8330_MASTVOL, CMI8330_MASTVOL, 4, 0, 15, 0),
 WSS_SINGLE("Loud Playback Switch", 0,