ALSA: sscape: constify pnp_card_device_id

pnp_card_device_id are not supposed to change at runtime. All functions
working with pnp_card_device_id provided by <linux/pnp.h> work with
const pnp_card_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/isa/sscape.c

···
 static int isa_registered;
 static int pnp_registered;
 
-static struct pnp_card_device_id sscape_pnpids[] = {
+static const struct pnp_card_device_id sscape_pnpids[] = {
 	{ .id = "ENS3081", .devs = { { "ENS0000" } } }, /* Soundscape PnP */
 	{ .id = "ENS4081", .devs = { { "ENS1011" } } },	/* VIVO90 */
 	{ .id = "" }	/* end */