NEW DELHI, April 11 (Reuters) - India and the U.S. have finalised terms of reference for talks over the first part of a bilateral trade deal, an Indian trade official said on Friday, adding it was possible that a "win-win" deal could take shape in the next 90 days. U.S. President Donald Trump on Wednesday announced a 90-day pause on most tariff hikes for major trading partners including India, while raising levies on China, providing temporary relief for Indian exporters.