Do not delete IPTV channel in DeleteChannel

The function DeleteChannel does not really delete a channel
but marks it for deletion when it is no longer referenced.
This is introduced in commit 2e26f7f.
Because the channel is not really deleted, as in removed from
the database, the associated record in table iptv_channel
should also not be deleted here.
The chhannel is removed from the database in a periodic
housekeeping task when there are no more recordings referencing
that channel and when at least one day has passed since the
channel was marked for deletion.
When the channel is finally deleted then also the corresponding
entry in iptv_channel, when it exists, should be deleted.

mythtv/libs/libmythtv/channelutil.cpp

@@ -1822,17 +1822,6 @@ bool ChannelUtil::DeleteChannel(uint channel_id)
         return false;
     }
 
-    query.prepare(
-        "DELETE FROM iptv_channel "
-        "WHERE chanid = :ID");
-    query.bindValue(":ID", channel_id);
-
-    if (!query.exec())
-    {
-        MythDB::DBError("Delete Channel 2", query);
-        return false;
-    }
-
     return true;
 }