* SPDR Gold Trust GLD, the world's largest gold-backed exchange-traded fund, said its holdings fell 0.13% to 914.17 tonnes on Tuesday. Jan 11 (Reuters) - Gold prices were flat on Wednesday, as traders awaited key U.S. inflation data due this week to gauge the Federal Reserve's rate hike stance. * Fed Governor Michelle Bowman said the U.S. central bank will have to raise interest rates further to combat high inflation and that will likely lead to softer job market conditions.