swarm-call: fix audio binding

Else the conference audio is not binded, and participants can only
listen to the host

Change-Id: I42075c2c5d5cb572efc8e679337f324cb39843b5

src/jamidht/jamiaccount.cpp

@@ -550,6 +550,7 @@ JamiAccount::handleIncomingConversationCall(const std::string& callId,
         }
 
         conf->addParticipant(callId);
+        conf->bindParticipant(callId);
         emitSignal<libjami::CallSignal::ConferenceChanged>(getAccountID(),
                                                            conf->getConfId(),
                                                            conf->getStateStr());