Bluetooth: Re-order clearing suspend tasks

Unregister_pm_notifier is a blocking call so suspend tasks should be
cleared beforehand. Otherwise, the notifier will wait for completion
before returning (and we encounter a 2s timeout on resume).

Fixes: 0e995280 (Bluetooth: Clear suspend tasks on unregister)
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>