By Bonnie Stiernberg Last night, hip-hop was finally front and center at the Super Bowl halftime show, as Dr. Dre was joined by Snoop Dogg, Kendrick Lamar, Eminem, 50 Cent and Mary J. Blige (along with Anderson .Paak, who made a brief appearance on drums). It was a long time coming for a league that has historically ignored the genre or relegated it to brief guest spots during more mainstream pop stars’ sets. But was it a genuine step in the right direction, or a calculated, sanitized PR move meant to deflect the accusations of racism that have long plagued the NFL? There was one moment in par…