GREENSBORO, N.C. — Dez Wells gave the floor a hard slap, and No. 2 Duke certainly felt it. It knocked the Blue Devils out of the Atlantic Coast Conference tournament early — and maybe off the No. 1 seed line for the NCAA tournament, too. Wells scored a career-high 30 points and Maryland upset Duke 83-74 on Friday night in the ACC tournament quarterfinals. Wells was 9 of 13 from the field and 10 of 10 from the free throw line to lead the seventh-seeded Terrapins (22-11), who delivered the first big shocker of the week in Greensboro and advanced …