[Refugees and migrants line up to receive a meal inside a terminal, moments after arriving aboard the Tera Jet passenger ship at the port of Piraeus]By Alastair Macdonald and Gabriela Baczynska BRUSSELS (Reuters) - The European Union took a step on Friday towards allowing for a two-year suspension of its prized free-travel Schengen zone to boost controls of the flows of people, acknowledging there is no quick fix in sight to the migration crisis engulfing the bloc. Greece, the main gateway to Europe for more than a million refugees and migrants last year, has been overwhelmed by the influx and other EU states have increasingly criticised Athens for not managing the flows properly. Several EU states including Germany, the main destination for people arriving in Europe from the Middle East and Africa, have quoted Greece's problems in temporarily reinstating emergency controls on some internal Schengen borders.