By Gabriel Crossley, David Brunnstrom and Michael Martina BEIJING/WASHINGTON (Reuters) – The United States on Thursday called on China to use its influence with Russia to urge a diplomatic solution to the Ukraine crisis, but policy experts doubted Beijing would back Washington in the standoff. China’s Foreign Minister Wang Yi spoke by phone with U.S. Secretary of State Antony Blinken and Beijing said it wanted all sides to remain calm and “refrain from doing things that agitate tensions and hype up the crisis.” Blinken stressed that tensions should be reduced and warned of the security and eco…