By Giuseppe Fonte and Elvira Pollina ROME (Reuters) – Italian state broadcaster RAI said on Thursday it plans to sell a stake of up to 15% in its TV tower company Rai Way, a move that Treasury sources said would leave the possibility of a long-awaited merger between the unit and rival EI Towers open. RAI will retain a majority stake, the broadcaster said in a statement, adding it would remain “open to assess further opportunities to develop Rai Way’s business”. The state TV broadcaster currently owns a 65% stake in Rai Way, whose shares extended earlier losses after the statement to be down al…