mcd_dispatcher_context_handler_done: remove the check for unhandled channels
mcd_dispatcher_context_handler_done: remove the check for unhandled channels

We always send all channels to the Handler together now, so this case
can no longer be achieved.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control