ALSA: drivers: make array 'names' const, reduces object code size

Don't populate array 'names' on the stack but instead make them static.
Makes the object code smaller by 50 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  21237	   9192	   1120	  31549	   7b3d	linux/sound/drivers/dummy.o

After:
   text	   data	    bss	    dec	    hex	filename
  21095	   9280	   1120	  31495	   7b07	linux/sound/drivers/dummy.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/dummy.c

@@ -830,7 +830,7 @@ static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_el
 static int snd_dummy_iobox_info(struct snd_kcontrol *kcontrol,
 				struct snd_ctl_elem_info *info)
 {
-	const char *const names[] = { "None", "CD Player" };
+	static const char *const names[] = { "None", "CD Player" };
 
 	return snd_ctl_enum_info(info, 1, 2, names);
 }