During an info session, Beth Flye (admissions director) had mentioned that this is probably the most common obvious mistake that she comes across in essays. She also mentioned that reviewers dont like seeing names of other schools in essays since it makes them look recycled.
That being said, I wouldn't think its a sure ding, if you have added sufficient research and enough passion about kellogg in your essays.
Just keep your fingers crossed. I dont think you can do anything about the typo... so don't worry.
Maybe other gmatclubbers can add more to this.