ALSA: rme9652: More constifications

Apply const prefix to the channel map tables.

Just for minor optimization and no functional changes.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/pci/rme9652/rme9652.c

···
 	int last_spdif_sample_rate;	/* so that we can catch externally ... */
 	int last_adat_sample_rate;	/* ... induced rate changes            */
 
-        char *channel_map;
+	const char *channel_map;
 
 	struct snd_card *card;
 	struct snd_pcm *pcm;
···
    where the data for that channel can be read/written from/to.
 */
 
-static char channel_map_9652_ss[26] = {
+static const char channel_map_9652_ss[26] = {
 	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
 	18, 19, 20, 21, 22, 23, 24, 25
 };
 
-static char channel_map_9636_ss[26] = {
+static const char channel_map_9636_ss[26] = {
 	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 
 	/* channels 16 and 17 are S/PDIF */
 	24, 25,
···
 	-1, -1, -1, -1, -1, -1, -1, -1
 };
 
-static char channel_map_9652_ds[26] = {
+static const char channel_map_9652_ds[26] = {
 	/* ADAT channels are remapped */
 	1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23,
 	/* channels 12 and 13 are S/PDIF */
···
 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
 };
 
-static char channel_map_9636_ds[26] = {
+static const char channel_map_9636_ds[26] = {
 	/* ADAT channels are remapped */
 	1, 3, 5, 7, 9, 11, 13, 15,
 	/* channels 8 and 9 are S/PDIF */