Service interruption via leaked device-tree references

Reference-count leakage in Linux pinctrl device-tree parsing allows local users to exhaust kernel resources and interrupt service. In pinctrl_dt_to_map(), a propname allocation failure leaves a previously acquired device-tree reference unreleased because the error path omits pinctrl_dt_free_maps(). Exploitation requires local low-privilege access and repeated reachability of that allocation-failure path; the bounded consequence is service interruption.