kobject: make get_ktype() take a const pointer

get_ktype() does not modify the structure passed to it, so mark the
parameter as being const to allow other const structures to be passed to
it in the future.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20221021072310.3931690-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/kobject.h

@@ -198,7 +198,7 @@ static inline void kset_put(struct kset *k)
 	kobject_put(&k->kobj);
 }
 
-static inline const struct kobj_type *get_ktype(struct kobject *kobj)
+static inline const struct kobj_type *get_ktype(const struct kobject *kobj)
 {
 	return kobj->ktype;
 }