My sense is that these phrases mean the same thing: the suspension has been reversed or nullfied.
Here's the Ngram, for what it's worth.
The fact that "lifted the suspension" is much more popular than "dropped the suspension" surprises me, since I'm inclined to think that the way to counteract a suspension should be to put it down, not further up.
So two questions.
(1) Is the Ngram right that we should prefer lift to drop in this context?
(2) Regardless of what is "right," how did the seemingly counter-intuitive phrase come to be the dominant one?