Bluetooth: BAP: Call bis_sync_req for all BIS sync state changes

Previously bis_sync_req was only called when requested_bis_sync
was changed. However that meant that there were cases where the
requested_bis_sync was the same as the new request, but where
the actual BIS sync state were different. This was mostly
the case when the scan delegator had autonousmly
added or modified the receive state.

Signed-off-by: Emil Gydesen <emil.gydesen@nordicsemi.no>