(Corrects advisory to say SSP Group's share move and response added in paragraphs 6 and 7, not 5 and 6) (Reuters) -Activist hedge fund Irenic Capital Management is trying to drum up interest in a take-private deal for Upper Crust owner SSP Group after boosting its stake in the food-to-go operator, the Financial Times reported on Thursday. Irenic Capital Management declined to comment. The New York-based hedge fund is encouraging private equity groups to launch takeover bids for the London-listed company ...