ALSA: drivers: mpu401: constify pnp_device_id

pnp_device_id are not supposed to change at runtime. All functions
working with pnp_device_id provided by <linux/pnp.h> work with
const pnp_device_id. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

sound/drivers/mpu401/mpu401.c

···
 
 #define IO_EXTENT 2
 
-static struct pnp_device_id snd_mpu401_pnpids[] = {
+static const struct pnp_device_id snd_mpu401_pnpids[] = {
 	{ .id = "PNPb006" },
 	{ .id = "" }
 };