dpll: zl3073x: use __dpll_device_change_ntf() and remove change_work

In the Linux kernel, the following vulnerability has been resolved: dpll: zl3073x: use __dpll_device_change_ntf() and remove change_work The change_work was introduced to send device change notifications from DPLL device callbacks without deadlocking on dpll_lock, since the callbacks are already invoked under that lock. Now that __dpll_device_change_ntf() is exported for callers that already hold dpll_lock, use it directly and remove the change_work infrastructure entirely. This eliminates a race condition where change_work could be re-scheduled after cancel_work_sync() during device teardown, potentially causing the handler to dereference a freed or NULL dpll_dev pointer.