MILAN (Reuters) – Italian broadcaster MediaForEurope (MFE) is preparing to seek regulatory clearance to raise its stake in ProSiebenSat.1 in a fresh sign of its commitment to the German rival, two sources close to the matter said. With a 23.9% stake, of which 2.29% held through financial instruments, MFE is the single largest shareholder in ProsiebenSat.1, an investment which has met with a lukewarm response from the Munich-based TV group. MFE’s board earlier this week gave its backing to filing documents with competition regulators to get the authorisations needed to raise its stake above 25%…