Do not allow channels to be inserted from xmltv for unsuitable source types

Primarily this means any digital tuner, DVB/ATSC/QAM256 etc

Inserting channels from xmltv guide data in these cases will result in duplicate
untunable channels as vital information such as network, service and transport
ids will not be available.

Author: stuartm

mythtv/programs/mythfilldatabase/channeldata.cpp

@@ -315,7 +315,7 @@ void ChannelData::handleChannels(int id, QList<ChanInfo> *chanlist)
                 }
             }
         }
-        else
+        else if (insert_chan(id)) // Only insert channels for non-scannable sources
         {
             int major, minor = 0;
             long long freq = 0;