Fix typo in precisionCaloMult

This is a fix for ATR-19848. A typo in _Mult function in TrigEgammaPrecisionCaloHypoTool.py was causing this:

https://gitlab.cern.ch/atlas/athena/blob/29d64a7ea1b9b58137d00fec42e130634210405a/Trigger/TrigHypothesis/TrigEgammaHypo/python/TrigEgammaPrecisionCaloHypoTool.py#L72