More cppcheck clean up

[analysisd/decoders/decoders_list.c:93]: (error) Memory leak: new_node
[analysisd/decoders/decoders_list.c:100]: (error) Memory leak: new_node
[analysisd/decoders/decoders_list.c:110]: (error) Memory leak: new_node
[analysisd/decoders/decoders_list.c:121]: (error) Memory leak: new_node