Bluetooth: hci_sync: Add support for waiting specific LE subevents

This adds support for waiting for specific LE subevents instead of
command status which may only indicate that the commands is in progress
and a different event is used to complete the operation.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>