xen: sysfs: 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>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20230216-kobj_type-xen-v1-1-742423de7d71@weissschuh.netSigned-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/sys-hypervisor.c

@@ -655,7 +655,7 @@ static const struct sysfs_ops hyp_sysfs_ops = {
 	.store = hyp_sysfs_store,
 };
 
-static struct kobj_type hyp_sysfs_kobj_type = {
+static const struct kobj_type hyp_sysfs_kobj_type = {
 	.sysfs_ops = &hyp_sysfs_ops,
 };