Shirt maker Phillips-Van Heusen (PVH) and Apax Partners, the British private equity group, are believed to have offered $700 million to buy fashion house Calvin Klein. Klein and his business partner Barry Schwartz are in advanced talks on the deal according to newspaper reports.   Also thought to be in the race to acquire the label, which was put up for sale in 1999 for $1 billion are VF Corporation, as well as Lawrence Stroll and Silas Chou, former co-chairmen of Tommy Hilfiger.