By Fayaz Bukhari SRINAGAR, India (Reuters) – A concert by renowned conductor Zubin Mehta in Indian-controlled Kashmir, where separatist groups are fighting New Delhi's rule, was mired in controversy on Sunday, posing potential diplomatic embarrassment for Germany, whose ambassador organized the event. The concert, on the banks of picturesque Dal Lake, went off peacefully on Saturday night amid heavy security to deter any attack by separatist insurgents in one of the most militarized regions of the world. …