Bluetooth: Simplify request cleanup code

Bluetooth: Simplify request cleanup code

The hci_req_sync_cancel() is just as much related to the request
cleanup as hci_request_cancel_all() is. Just move the former into the
latter and do the cleanup from a single place in hci_dev_do_close().
The important thing is to avoid deadlocks by holding the req_sync
lock: previously hci_request_cancel_all was done right after releasing
the lock and with this patch it's right before taking it.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>