PRECIOUS-Gold steady ahead of speech by Fed's Yellen

* Yellen due to speak in London on Tuesday * Gold steady after falling to near six-week low hit on Monday * Platinum close to over six-week lows reached on Monday (Adds comment, updates prices) By Nithin ThomasPrasad BENGALURU, June 27 (Reuters) - Gold held steady on Tuesday supported by an easing dollar, with investors looking to a speech later in the day by Federal Reserve Chair Janet Yellen for clues on the outlook for U.S. monetary policy. Yellen is scheduled to tak