Ice Cube's a Raider Fan FOR LIFE ... Even In Vegas??

He's one of the biggest Raider fans on the planet -- but if the Silver & Black move straight outta Cali and into Las Vegas, is that a deal breaker for Ice Cube???

That's what we asked the rapper at LAX -- you know, since Raiders owner Mark Davis announced he's dead set on taking his team to Sin City in the next few years.