Remember, different races have different average IQs. If a race has a lower average IQ no amount of AA will make them succeed at college exactly the same as another race.
IQ isn't something set in stone, nor is it entirely driven by genetics. Even the smallest, most inconsequential thing that you wouldn't normally associate with intelligence, like food, can fluctuate that average by quite a bit. Proper nutrition can boost average IQ scores by at least 10 points or so up to the median.
I remember reading awhile back that some scientists had attempted to discover a set of genes that could attribute to intelligence. They found three, I believe, but the advantages it bestowed upon those lucky enough to have them were so slight, it was barely worth considering on a sociological scale. Those who had the genes were, on average scoring 1-3 points higher on IQ tests than those who didn't.
You can't really say that IQ is defined along racial lines. It's more determined by conditions and culture. We'll take Asian people as an example, since they tend to be considered a pretty smart bunch. There isn't anything in the Asian genetic code that naturally makes them more intelligent than white, black, Hispanic, or Jewish people. It's the fact that most Asian nations are stable and wealthy, plus the fact they put such a huge cultural emphasis on academic excellence, that makes it a natural thing that they produce more intelligent people on average.