LL_CIS_IND starts a ticker for the created CIG, using the event_counter
and offset provided. Ticker generates callbacks to
lll_peripheral_iso_prepare. Event done with ISO (extra) type is demuxed
and done handled for CIG including ticker update with drift
compensation.
TODO: Handle multiple CISes as well as pause/resume and scheduling
latency.
Signed-off-by: Morten Priess <mtpr@oticon.com>