ALSA: jack: More constification

Apply const prefix to the static jack switch table.

Just for minor optimization and no functional changes.

Link: https://lore.kernel.org/r/20200105144823.29547-40-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/jack.c

@@ -19,7 +19,7 @@ struct snd_jack_kctl {
 };
 
 #ifdef CONFIG_SND_JACK_INPUT_DEV
-static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
+static const int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
 	SW_HEADPHONE_INSERT,
 	SW_MICROPHONE_INSERT,
 	SW_LINEOUT_INSERT,