It depends on how you define racism. According to the politically correct definition racism is not just prejudice but prejudice plus power. Since only whites and men have the power, only they can be racist or sexist. By definition, women and minorities cannot be sexist or racist.
This is the definition given in "Class, Race, and Gender" that is a widely used text in college sociology, political science, and women's studies courses.
I think anybody can be racist and that the term only applies to race--not ethnic groups (Hispanics), religion (Muslims), or other groups that are not a race.