fix IP2IP account signal at creation

When IP2IP account is created only AccountsChanged signal is emited.
But doRegister() method is called and this kind of account must succeed
on such (as there is no registration) and must call
setRegistrationState(RegistrationState::REGISTERED) to make aware the client
on this event.
This was not done. This patch adds this call.

Change-Id: Ic5b8a31d9e2b98dd96ed394247f77bbfa3d8cdde
Reviewed-by: Andreas Traczyk <andreas.traczyk@savoirfairelinux.com>

src/sip/sipaccount.cpp

@@ -806,6 +806,7 @@ void SIPAccount::doRegister2_()
             setTransport(link_->sipTransportBroker->getUdpTransport(
                 SipTransportDescr { getTransportType(), getLocalPort(), getLocalInterface() }
             ));
+        setRegistrationState(RegistrationState::REGISTERED);
         return;
     }