DeleteAllInputs must not delete iptv_channel (#987)

The CardUtil function DeleteAllInputs does delete the
content of all four tables related to inputs but it does
also delete the content of table iptv_channel.
This is not correct; table iptv_channel contains the URLs
of the channels that are IPTV channels.
This bug has been introduced as part of commit d4c0f13.
The entries in table iptv_channel can only be removed
when the corresponding channel has been deleted.
This is done as part of a periodic housekeeping task.

Refs #936

mythtv/libs/libmythtv/cardutil.cpp

@@ -2894,8 +2894,7 @@ bool CardUtil::DeleteAllInputs(void)
     return (query.exec("TRUNCATE TABLE inputgroup") &&
             query.exec("TRUNCATE TABLE diseqc_config") &&
             query.exec("TRUNCATE TABLE diseqc_tree") &&
-            query.exec("TRUNCATE TABLE capturecard") &&
-            query.exec("TRUNCATE TABLE iptv_channel"));
+            query.exec("TRUNCATE TABLE capturecard"));
 }
 
 std::vector<uint> CardUtil::GetInputList(void)