Whoever the Knicks face in the Eastern Conference finals, whether it is the Pistons or Cavaliers, will be a team coming off back-to-back seven-game series. Both teams went the distance in the opening round and the two will meet Sunday night in a winner-take-all Game 7 in Detroit. The Knicks, meanwhile, will have a nine-day layoff between games by the time the next series begins Tuesday night. Is that an advantage? Coach Mike Brown isn’t certain. “I’ve been in both situations, playing while a