topology: ignore cfm packets on packet in
topology: ignore cfm packets on packet in

This commit will allow the host_discovery_packet_in_handler to ignore invalid
cfm packets. Ryu will fail to parse cfm packets with an interval of 0 -- We
discovered this when one of our systems sent cfm packets with an interval of 0.

Signed-off-by: Evan Gray <c2f69a330093c59973f94376329201e16e1fffe7@gmail.com>
Reviewed-by: Iwase Yusuke <bb80e84cc9f5a8f01385872ee89032beb5d4eba7@gmail.com>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

lagopus/ryu-lagopus-ext,fujita/ryu,gareging/SDN_Framework,lagopus/ryu-lagopus-ext,shinpeimuraoka/ryu,shinpeimuraoka/ryu,TakeshiTseng/ryu,lagopus/ryu-lagopus-ext,fkakuma/ryu,TakeshiTseng/ryu,pichuang/ryu,fujita/ryu,pichuang/ryu,osrg/ryu,fkakuma/ryu,pichuang/ryu,iwaseyusuke/ryu,fkakuma/ryu,iwaseyusuke/ryu,gareging/SDN_Framework,gareging/SDN_Framework,osrg/ryu,pichuang/ryu,TakeshiTseng/ryu,iwaseyusuke/ryu,shinpeimuraoka/ryu,fujita/ryu,fujita/ryu,TakeshiTseng/ryu,TakeshiTseng/ryu,gareging/SDN_Framework,shinpeimuraoka/ryu,fkakuma/ryu,lagopus/ryu-lagopus-ext,iwaseyusuke/ryu,pichuang/ryu,fujita/ryu,shinpeimuraoka/ryu,osrg/ryu,fkakuma/ryu,gareging/SDN_Framework,lagopus/ryu-lagopus-ext,osrg/ryu,iwaseyusuke/ryu,osrg/ryu