No, felon disenfranchisement laws are not a form of racial discrimination, because something is not racist only because it has a racially-disproportionate effect. It's similar to African-Americans in the NBA. The NBA does not discriminate against white people simply because there are very few of them in the NBA. If more minorities commit crimes, it is only fair that they do not vote.
Felons, by their name, have obviously done something very bad to get to where they are in their lives, so they should not be allowed to vote. Voting is a privilege and something that should be taken very seriously by people who have done little wrong in their lives, so barring felons from voting is okay.