of: make of_node_ktype constant

Since commit ee6d3dd4ed48 ("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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

drivers/of/kobj.c

···
 }
 #endif /* CONFIG_OF_DYNAMIC */
 
-struct kobj_type of_node_ktype = {
+const struct kobj_type of_node_ktype = {
 	.release = of_node_release,
 };
 

include/linux/of.h

···
 };
 
 /* initialize a node */
-extern struct kobj_type of_node_ktype;
+extern const struct kobj_type of_node_ktype;
 extern const struct fwnode_operations of_fwnode_ops;
 static inline void of_node_init(struct device_node *node)
 {