ALSA: hda: make kobj_type structure constant

Since commit ee6d3dd4 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definition to prevent
modification at runtime.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230211-kobj_type-sound-v1-1-17107ceb25b7@weissschuh.netSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/hda/hdac_sysfs.c

@@ -148,7 +148,7 @@ static void widget_release(struct kobject *kobj)
 	kfree(kobj);
 }
 
-static struct kobj_type widget_ktype = {
+static const struct kobj_type widget_ktype = {
 	.release	= widget_release,
 	.sysfs_ops	= &widget_sysfs_ops,
 };