vrxtx/rtsp: update printed name

replace "H264 standard" with "RTP standard (using RTSP)" - the "standard"
protocol (on the sender) is no longer restricted to H264 - JPEG is also
possible as well as couple of audio codecs.

src/video_rxtx/h264_rtp.cpp

@@ -210,7 +210,7 @@ static video_rxtx *create_video_rxtx_h264_std(std::map<std::string, param_u> con
 }
 
 static const struct video_rxtx_info h264_video_rxtx_info = {
-        "H264 standard",
+        "RTP standard (using RTSP)",
         create_video_rxtx_h264_std
 };