BRUSSELS, Sept 30 - Inflation in the euro zone was steady at 2.1 percent in September from August, remaining above the European Central Bank's threshold for a second month in a row, Eurostat data showed on Tuesday. Eurostat's first estimate of inflation in the 12-region euro zone follows a rise in Italian consumer prices in September to their highest rate this year, while German inflation in the same month was unchanged at 1.1 percent year-on-year. Economists polled by had expected the early estimate of inflation to ease to 2.0 percent ion September//