The official name, and perhaps even the official logo, have been online for quite some time over at ParkRumors.com, but I guess no one noticed or cared? Here's the image, from a pressed penny machine that was in CityWalk and later removed/changed I guess:
http://uor.parkrumors.com/despicable-me-minion-mayhem/
Universal even recently filed a trademark for the use of the name "Despicable Me: Minion Mayhem", so I'm assuming that's pretty much the finalized name for the ride...