Fix wrong call method

Author: artemkrachulov

MatrixSDK/VoIP/MXCall.m

@@ -1167,7 +1167,7 @@ - (void)handleCallInvite:(MXEvent *)event
             [self.audioOutputRouter reroute];
 #endif
 
-            [self->callStackCall handleAnswer:self->callInviteEventContent.offer.sdp
+            [self->callStackCall handleOffer:self->callInviteEventContent.offer.sdp
                                      success:^{
                 MXStrongifyAndReturnIfNil(self);