rtsp: fix video msg path

This fixed RTSP being broken since the commit 9c3fc10 (26th Mar),
where the changed path has been fixed in control-socket but not in RTSP.

Author: MartinPulec

src/rtsp/BasicRTSPOnlySubsession.cpp

@@ -73,6 +73,7 @@ constexpr enum module_class path_sender_audio[] = { MODULE_CLASS_AUDIO,
                                                     MODULE_CLASS_SENDER,
                                                     MODULE_CLASS_NONE };
 constexpr enum module_class path_sender_video[] = { MODULE_CLASS_SENDER,
+                                                    MODULE_CLASS_DATA,
                                                     MODULE_CLASS_NONE };
 
 BasicRTSPOnlySubsession::BasicRTSPOnlySubsession(UsageEnvironment& env,