Bluetooth: hci_core: Fix UAF in hci_unregister_dev()

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_core: Fix UAF in hci_unregister_dev() hci_unregister_dev() does not disable cmd_timer and ncmd_timer before the hci_dev structure is freed. If a timeout fires during device teardown, the callback dereferences freed memory (including the hdev->reset function pointer), leading to a use-after-free. Add disable_delayed_work_sync() calls alongside the existing disable_work_sync() calls to ensure both timers are fully quiesced before teardown proceeds.