CVE-2026-63977: dpll: zl3073x: use __dpll_device_change_ntf() and remove change_work

In the Linux kernel, the following vulnerability has been resolved:

dpll: zl3073x: use dplldevicechangentf() and remove changework

The changework was introduced to send device change notifications from DPLL device callbacks without deadlocking on dplllock, since the callbacks are already invoked under that lock. Now that dplldevicechangentf() is exported for callers that already hold dplllock, use it directly and remove the changework infrastructure entirely.

This eliminates a race condition where changework could be re-scheduled after cancelworksync() during device teardown, potentially causing the handler to dereference a freed or NULL dplldev pointer.