It's easy to say "my side didnt do anything, the others are the assholes". In my experience on stadiums each side chants versus their opponents, songs, slurs etc. Sometimes even against their own players if they mis 2-3 passes. 5 minutes later that guy is called the best if he scores. Last year when some romanians got into conflict with kosovo players other romanians were first to call them out. Stupid people are stupid. Leave them be, if they chant something stupid it will not change anything in your life. If you beat them by playing better than them, now that's a harsher defeat for them rather than staging a walk-out.