ALSA: sparc: 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/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/sparc/amd7930.c

···
 	return change;
 }
 
-static struct snd_kcontrol_new amd7930_controls[] = {
+static const struct snd_kcontrol_new amd7930_controls[] = {
 	{
 		.iface		=	SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name		=	"Monitor Volume",

sound/sparc/cs4231.c

···
   .private_value = (left_reg) | ((right_reg) << 8) | ((shift_left) << 16) | \
 		   ((shift_right) << 19) | ((mask) << 24) | ((invert) << 22) }
 
-static struct snd_kcontrol_new snd_cs4231_controls[] = {
+static const struct snd_kcontrol_new snd_cs4231_controls[] = {
 CS4231_DOUBLE("PCM Playback Switch", 0, CS4231_LEFT_OUTPUT,
 		CS4231_RIGHT_OUTPUT, 7, 7, 1, 1),
 CS4231_DOUBLE("PCM Playback Volume", 0, CS4231_LEFT_OUTPUT,

sound/sparc/dbri.c

···
   .private_value = (entry) | ((shift) << 8) | ((mask) << 16) |	\
 			((invert) << 24) },
 
-static struct snd_kcontrol_new dbri_controls[] = {
+static const struct snd_kcontrol_new dbri_controls[] = {
 	{
 	 .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	 .name  = "Playback Volume",