Bluetooth: hci_sync: Introduce hci_cmd_sync_run/hci_cmd_sync_run_once

This introduces hci_cmd_sync_run/hci_cmd_sync_run_once which acts like
hci_cmd_sync_queue/hci_cmd_sync_queue_once but runs immediately when
already on hdev->cmd_sync_work context.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>