ALSA: ali5451: Constify hw_constraints

snd_pcm_hw_constraint_list(), *_ratnums() and *_ratdens() receive the
const pointers.  Constify the corresponding static objects for better
hardening.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/ali5451/ali5451.c

@@ -1602,8 +1602,8 @@ static struct snd_pcm_hardware snd_ali_modem =
 static int snd_ali_modem_open(struct snd_pcm_substream *substream, int rec,
 			      int channel)
 {
-	static unsigned int rates[] = {8000, 9600, 12000, 16000};
-	static struct snd_pcm_hw_constraint_list hw_constraint_rates = {
+	static const unsigned int rates[] = {8000, 9600, 12000, 16000};
+	static const struct snd_pcm_hw_constraint_list hw_constraint_rates = {
 		.count = ARRAY_SIZE(rates),
 		.list = rates,
 		.mask = 0,