A brash, confident David Haye is going for a knockout Saturday against 2-time and reigning WBA heavyweight champion Nikolai Valuev in their 12-round title fight headlining the “David vs. Goliath” Pay-Per-View event being shown in North American live from Nuremberg, Germany. Haye, (22-1, 21 KOs), from London, ruled the cruiserweight division as unified champion –…