By Shashank Nayar and Ambar Warrick (Reuters) -London’s FTSE 100 rose on Wednesday with heavyweight mining, energy and banking shares leading gains before the outcome of a U.S. Federal Reserve meeting, while Playtech dropped on reports of a potential breakup. The blue-chip FTSE 100 rose 1.3% with Royal Dutch Shell, Glencore and HSBC Holdings the top boosts to the index. The banking sub-index rose 2.6%, tracking higher yields. Expectations of rising interest rates have boosted bank stocks this year. Global shares steadied after sharp losses earlier this week as investors awaited any hints about…