If I had to hazard a guess, I think it's likely Trump would have have an IQ measurement in the 120-140 range.
However, that's largely irrelevant. Politics is ultimately an argument over moral principles, not who has the best words or who can solve differential equations more quickly.
The Donald is a very bright man...who has put his intellectual abilities almost entirely into self-aggrandizement rather than in the service of the greater good.
Trump has exhibited no signs of superior intelligence. In fact, he has shown an inability to grasp many issues which is primarily the reason why he rarely discusses them. Trump is an outer-borough Queens boy who tried to make it in Manhattan. The best way to understand Trump is that he is a social climber in desperate need of adulation.
I don't think his would be particularly high -- perhaps less than 130. Clearly he needed a lot of animal cunning to have succeeded in the business world, but much of that comes down to greed and lack of scruples. Winning the presidency probably had less to do with any personal qualification than the Democrats' failure to take him seriously or, perhaps, to field a stronger candidate.