NEW YORK (Reuters) - U.S. civil rights activist Al Sharpton weighed into a fight over an Arizona sheriff's immigration sweeps on Tuesday, accusing him of racially profiling Hispanics and urging him to step down. Maricopa County Sheriff Joe Arpaio has dispatched deputies into Hispanic communities in the Phoenix area, where they stop people and arrest anyone who cannot prove he or she is a legal U.S. resident. Under a deal allowing them to enforce federal immigration laws, the deputies have arrested more than 1,500 people who they determined were in Arizona illegally, triggering street protests and condemnation from Latino activists...