dpll: zl3073x: use __dpll_device_change_ntf() and remove change_work

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.

Fixes: 9363b4837659 ("dpll: zl3073x: Allow to configure phase offset averaging factor")
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Link: https://patch.msgid.link/20260526074525.1451008-3-ivecera@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>