x86/MCE/AMD: Make kobj_type structure constant

Since

  ee6d3dd ("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>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230217-kobj_type-mce-amd-v1-1-40ef94816444@weissschuh.net

Author: t-8ch

arch/x86/kernel/cpu/mce/amd.c

@@ -1029,7 +1029,7 @@ static const struct sysfs_ops threshold_ops = {
 
 static void threshold_block_release(struct kobject *kobj);
 
-static struct kobj_type threshold_ktype = {
+static const struct kobj_type threshold_ktype = {
 	.sysfs_ops		= &threshold_ops,
 	.default_groups		= default_groups,
 	.release		= threshold_block_release,