Use transport stream ID to identify full transport stream channels

In mythtv-setup, the additional channels created when the
"Add full Transport Stream channels" option is selected get names
like MPTS_123 where, for DVB systems, 123 is the service ID
of the one of the channels in the transport stream.
As the MPTS channels capture the complete transport stream it is
better to identify them with the transport stream ID.
This is now implemented with the transport stream ID as found in the PAT.

mythtv/libs/libmythtv/channelscan/channelscan_sm.cpp

@@ -1533,6 +1533,8 @@ ScanDTVTransportList ChannelScanSM::GetChannelList(bool addFullTS) const
                 else if (info.m_atsc_major_channel > 0)
                     info.m_callsign =
                         QString("MPTS_%1").arg(info.m_atsc_major_channel);
+                else if (info.m_pat_tsid > 0)
+                    info.m_callsign = QString("MPTS_%1").arg(info.m_pat_tsid);
                 else if (info.m_service_id > 0)
                     info.m_callsign = QString("MPTS_%1").arg(info.m_service_id);
                 else if (!info.m_chan_num.isEmpty())