Herschel Walker -- My Son's a World Champ ... Crushed Huge Cheerleading Tourney (VIDEO)

Herschel Walker's 16-year-old cheerleader son did something the ex-NFL star never did ... WON A WORLD CHAMPIONSHIP -- and Herschel says he couldn't be more proud!  Herschel was out in D.C. Tuesday when we asked about Christian Walker -- a…