Fix a copy and paste error in the clone filter.
Fix a copy and paste error in the clone filter.

It was still using a variable name from the split filter.

joekiller/logstash-kafka,opentable/logstash-kafka,Aloomaio/logstash-kafka,opentable/logstash-kafka,joekiller/logstash-kafka,Aloomaio/logstash-kafka,tinglinux/logstash-kafka,tinglinux/logstash-kafka